Add changelog entry

Author: brianschubert

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Unreleased
 
+- Fix incorrect behaviour on PyPy 3.9 and PyPy 3.10 that meant that the result of
+  calling `isinstance` with `typing_extensions.Concatenate[...]` or
+  `typing_extensions.Unpack[...]` as the first argument could have a different
+  result in some situations depending on whether or not a profiling function had been
+  set using `sys.setprofile`. Patch by Brian Schubert.
 - Raise `TypeError` when attempting to subclass `typing_extensions.ParamSpec` on
   Python 3.9. The `typing` implementation has always raised an error, and the
   `typing_extensions` implementation has raised an error on Python 3.10+ since