Remove support for python 3.8 (#17908)

### Pull Request Checklist

<!-- Please read
https://element-hq.github.io/synapse/latest/development/contributing_guide.html
before submitting your pull request -->

* [X] Pull request is based on the develop branch
* [X] Pull request includes a [changelog
file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog).
The entry should:
- Be a short description of your change which makes sense to users.
"Fixed a bug that prevented receiving messages from other servers."
instead of "Moved X method from `EventStore` to `EventWorkerStore`.".
  - Use markdown where necessary, mostly for `code blocks`.
  - End with either a period (.) or an exclamation mark (!).
  - Start with a capital letter.
- Feel free to credit yourself, by adding a sentence "Contributed by
@github_username." or "Contributed by [Your Name]." to the end of the
entry.
* [X] [Code
style](https://element-hq.github.io/synapse/latest/code_style.html) is
correct
(run the
[linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))

---------

Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>

tests/handlers/test_federation.py

@@ -661,9 +661,12 @@ class PartialJoinTestCase(unittest.FederatingHomeserverTestCase):
             )
         )
 
-        with patch.object(
-            fed_client, "make_membership_event", mock_make_membership_event
-        ), patch.object(fed_client, "send_join", mock_send_join):
+        with (
+            patch.object(
+                fed_client, "make_membership_event", mock_make_membership_event
+            ),
+            patch.object(fed_client, "send_join", mock_send_join),
+        ):
             # Join and check that our join event is rejected
             # (The join event is rejected because it doesn't have any signatures)
             join_exc = self.get_failure(
@@ -708,9 +711,12 @@ class PartialJoinTestCase(unittest.FederatingHomeserverTestCase):
         fed_handler = self.hs.get_federation_handler()
         store = self.hs.get_datastores().main
 
-        with patch.object(
-            fed_handler, "_sync_partial_state_room", mock_sync_partial_state_room
-        ), patch.object(store, "is_partial_state_room", mock_is_partial_state_room):
+        with (
+            patch.object(
+                fed_handler, "_sync_partial_state_room", mock_sync_partial_state_room
+            ),
+            patch.object(store, "is_partial_state_room", mock_is_partial_state_room),
+        ):
             # Start the partial state sync.
             fed_handler._start_partial_state_room_sync("hs1", {"hs2"}, "room_id")
             self.assertEqual(mock_sync_partial_state_room.call_count, 1)
@@ -760,9 +766,12 @@ class PartialJoinTestCase(unittest.FederatingHomeserverTestCase):
         fed_handler = self.hs.get_federation_handler()
         store = self.hs.get_datastores().main
 
-        with patch.object(
-            fed_handler, "_sync_partial_state_room", mock_sync_partial_state_room
-        ), patch.object(store, "is_partial_state_room", mock_is_partial_state_room):
+        with (
+            patch.object(
+                fed_handler, "_sync_partial_state_room", mock_sync_partial_state_room
+            ),
+            patch.object(store, "is_partial_state_room", mock_is_partial_state_room),
+        ):
             # Start the partial state sync.
             fed_handler._start_partial_state_room_sync("hs1", {"hs2"}, "room_id")
             self.assertEqual(mock_sync_partial_state_room.call_count, 1)

tests/handlers/test_room_member.py

@@ -172,20 +172,25 @@ class TestJoinsLimitedByPerRoomRateLimiter(FederatingHomeserverTestCase):
             )
         )
 
-        with patch.object(
-            self.handler.federation_handler.federation_client,
-            "make_membership_event",
-            mock_make_membership_event,
-        ), patch.object(
-            self.handler.federation_handler.federation_client,
-            "send_join",
-            mock_send_join,
-        ), patch(
-            "synapse.event_auth._is_membership_change_allowed",
-            return_value=None,
-        ), patch(
-            "synapse.handlers.federation_event.check_state_dependent_auth_rules",
-            return_value=None,
+        with (
+            patch.object(
+                self.handler.federation_handler.federation_client,
+                "make_membership_event",
+                mock_make_membership_event,
+            ),
+            patch.object(
+                self.handler.federation_handler.federation_client,
+                "send_join",
+                mock_send_join,
+            ),
+            patch(
+                "synapse.event_auth._is_membership_change_allowed",
+                return_value=None,
+            ),
+            patch(
+                "synapse.handlers.federation_event.check_state_dependent_auth_rules",
+                return_value=None,
+            ),
         ):
             self.get_success(
                 self.handler.update_membership(

tests/push/test_bulk_push_rule_evaluator.py

@@ -120,9 +120,11 @@ class TestBulkPushRuleEvaluator(HomeserverTestCase):
         #
         # We have seen stringy and null values for "room" in the wild, so presumably
         # some of this validation was missing in the past.
-        with patch("synapse.events.validator.validate_canonicaljson"), patch(
-            "synapse.events.validator.jsonschema.validate"
-        ), patch("synapse.handlers.event_auth.check_state_dependent_auth_rules"):
+        with (
+            patch("synapse.events.validator.validate_canonicaljson"),
+            patch("synapse.events.validator.jsonschema.validate"),
+            patch("synapse.handlers.event_auth.check_state_dependent_auth_rules"),
+        ):
             pl_event_id = self.helper.send_state(
                 self.room_id,
                 "m.room.power_levels",

tests/storage/test_stream.py

@@ -1465,20 +1465,25 @@ class GetCurrentStateDeltaMembershipChangesForUserFederationTestCase(
             )
         )
 
-        with patch.object(
-            self.room_member_handler.federation_handler.federation_client,
-            "make_membership_event",
-            mock_make_membership_event,
-        ), patch.object(
-            self.room_member_handler.federation_handler.federation_client,
-            "send_join",
-            mock_send_join,
-        ), patch(
-            "synapse.event_auth._is_membership_change_allowed",
-            return_value=None,
-        ), patch(
-            "synapse.handlers.federation_event.check_state_dependent_auth_rules",
-            return_value=None,
+        with (
+            patch.object(
+                self.room_member_handler.federation_handler.federation_client,
+                "make_membership_event",
+                mock_make_membership_event,
+            ),
+            patch.object(
+                self.room_member_handler.federation_handler.federation_client,
+                "send_join",
+                mock_send_join,
+            ),
+            patch(
+                "synapse.event_auth._is_membership_change_allowed",
+                return_value=None,
+            ),
+            patch(
+                "synapse.handlers.federation_event.check_state_dependent_auth_rules",
+                return_value=None,
+            ),
         ):
             self.get_success(
                 self.room_member_handler.update_membership(

tests/util/test_check_dependencies.py

@@ -109,10 +109,13 @@ class TestDependencyChecker(TestCase):
 
     def test_checks_ignore_dev_dependencies(self) -> None:
         """Both generic and per-extra checks should ignore dev dependencies."""
-        with patch(
-            "synapse.util.check_dependencies.metadata.requires",
-            return_value=["dummypkg >= 1; extra == 'mypy'"],
-        ), patch("synapse.util.check_dependencies.RUNTIME_EXTRAS", {"cool-extra"}):
+        with (
+            patch(
+                "synapse.util.check_dependencies.metadata.requires",
+                return_value=["dummypkg >= 1; extra == 'mypy'"],
+            ),
+            patch("synapse.util.check_dependencies.RUNTIME_EXTRAS", {"cool-extra"}),
+        ):
             # We're testing that none of these calls raise.
             with self.mock_installed_package(None):
                 check_requirements()
@@ -141,10 +144,13 @@ class TestDependencyChecker(TestCase):
 
     def test_check_for_extra_dependencies(self) -> None:
         """Complain if a package required for an extra is missing or old."""
-        with patch(
-            "synapse.util.check_dependencies.metadata.requires",
-            return_value=["dummypkg >= 1; extra == 'cool-extra'"],
-        ), patch("synapse.util.check_dependencies.RUNTIME_EXTRAS", {"cool-extra"}):
+        with (
+            patch(
+                "synapse.util.check_dependencies.metadata.requires",
+                return_value=["dummypkg >= 1; extra == 'cool-extra'"],
+            ),
+            patch("synapse.util.check_dependencies.RUNTIME_EXTRAS", {"cool-extra"}),
+        ):
             with self.mock_installed_package(None):
                 self.assertRaises(DependencyException, check_requirements, "cool-extra")
             with self.mock_installed_package(old):