Move warning up to the top

CHANGES.md

@@ -1,5 +1,8 @@
 # Synapse 1.87.0 (2023-07-04)
 
+Please note that this will be the last release of Synapse that is compatible with
+Python 3.7 and earlier.
+
 ### Bugfixes
 
 - Pin `pydantic` to `^1.7.4` to avoid backwards-incompatible API changes from the 2.0.0 release.
@@ -13,9 +16,6 @@
 
 # Synapse 1.87.0rc1 (2023-06-27)
 
-Please note that this will be the last release of Synapse that is compatible with
-Python 3.7 and earlier.
-
 ### Features
 
 - Improve `/messages` response time by avoiding backfill when we already have messages to return. ([\#15737](https://github.com/matrix-org/synapse/issues/15737))