Add whatsnew entry

Author: ashkop

Doc/whatsnew/3.10.rst

@@ -92,6 +92,9 @@ Other Language Changes
   the :meth:`~object.__int__` method but do not have the
   :meth:`~object.__index__` method).
   (Contributed by Serhiy Storchaka in :issue:`37999`.)
+* If :func:`object.__ipow__` returns :const:`NotImplemented`, the operator will
+  correctly fall back to :func:`object.__pow__` and :func:`object.__rpow__` as expected.
+  (Contributed by Alex Shkop in :issue:`38302`.)
 
 
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