Add sqlite deprecation to changelog and upgrade notes

CHANGES.md

@@ -7,6 +7,14 @@ deprecation
 policy](https://element-hq.github.io/synapse/latest/deprecation_policy.html#platform-dependencies),
 as it is now [end of life](https://endoflife.date/python).
 
+## SQLite 3.40.0+ is now required.
+
+The minimum supported SQLite version has been increased from 3.27.0 to 3.40.0.
+
+If you use current versions of the
+[matrixorg/synapse](setup/installation.html#docker-images-and-ansible-playbooks)
+Docker images, no action is required.
+
 
 ## Deprecation of MacOS Python wheels