updated changelog

Author: Daraan

CHANGELOG.md

@@ -16,6 +16,9 @@
   subscripted objects) had wrong parameters if they were directly
   subscripted with an `Unpack` object.
   Patch by [Daraan](https://github.com/Daraan).
+  - Backport of CPython PR [#124795](https://github.com/python/cpython/pull/124795)
+  and fix that `TypeAliasType` not raising an error on non-tupple inputs for `type_params`.
+  Patch by [Daraan](https://github.com/Daraan).
 
 # Release 4.12.2 (June 7, 2024)