changelog entry for the TypeAliasType union fix

Author: jorenham

CHANGELOG.md

@@ -5,6 +5,9 @@ Bugfixes:
   Patch by [Daraan](https://github.com/Daraan).
 - Fix `TypeError` when using `evaluate_forward_ref` on Python 3.10.1-2 and 3.9.8-10.
   Patch by [Daraan](https://github.com/Daraan).
+- Fix `TypeError` when taking the union of `typing_extensions.TypeAliasType` and a
+  `typing.TypeAliasType` on Python 3.12 and 3.13.
+  Patch by [Joren Hammudoglu](https://github.com/jorenham).
 
 # Release 4.13.0 (March 25, 2025)