Fix a typo in check_dependencies.py which makes setuptools_rust a running dependency (#19417)

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There is a typo in check_dependencies.py which makes setuptools_rust a
runtime requirement, but there is no need for it at runtime. This patch
solves the typo. I tested starting 1.146.0 with this patch and without
setuptools_rust and it starts correctly

changelog.d/19417.bugfix

@@ -0,0 +1 @@
+Fix a typo that incorrectly made `setuptools_rust` a runtime dependency.

synapse/util/check_dependencies.py

@@ -32,6 +32,7 @@ from typing import Any, Iterable, NamedTuple, Sequence, cast
 
 from packaging.markers import Marker, Value, Variable, default_environment
 from packaging.requirements import Requirement
+from packaging.utils import canonicalize_name
 
 DISTRIBUTION_NAME = "matrix-synapse"
 
@@ -96,7 +97,7 @@ def _should_ignore_runtime_requirement(req: Requirement) -> bool:
     # In any case, workaround this by ignoring setuptools_rust here. (It might be
     # slightly cleaner to put `setuptools_rust` in a `build` extra or similar, but for
     # now let's do something quick and dirty.
-    if req.name == "setuptools_rust":
+    if canonicalize_name(req.name) == "setuptools-rust":
         return True
     return False
 

tests/util/test_check_dependencies.py

@@ -201,13 +201,13 @@ class TestDependencyChecker(TestCase):
         """
         with patch(
             "synapse.util.check_dependencies.metadata.requires",
-            return_value=["setuptools_rust >= 1.3"],
+            return_value=["setuptools-rust >= 1.3"],
         ):
             with self.mock_installed_package(None):
-                # should not raise, even if setuptools_rust is not installed
+                # should not raise, even if setuptools-rust is not installed
                 check_requirements()
             with self.mock_installed_package(old):
-                # We also ignore old versions of setuptools_rust
+                # We also ignore old versions of setuptools-rust
                 check_requirements()
 
     def test_python_version_markers_respected(self) -> None: