Update changelog.

CHANGES.rst

@@ -21,6 +21,9 @@ Features added
   these dependencies.  Already available in Cython :ref:`0.29.27`.
   Patch by Evgeni Burovski.  (Github issue :issue:`1214`)
 
+* ``cythonize()`` and the corresponding CLI command now regenerate the output files
+  also when they already exist but were generated by a different Cython version.
+
 * The generated C code now compiles in CPython 3.11a4.
   (Github issue :issue:`4500`)