[3.13] Fix the doctest.testmod() docstring (GH-136675) (GH-136691)

__test__ = None is not supported since Python 2.4.
(cherry picked from commit cb59eaefeda5ff44ac0c742bff2b8afc023be313)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Miss Islington (bot) committed 10mo ago

3e0ead0756063c4e5ccd4ab91ced156938b67bd7

Parent: 894d30c

Committed by GitHub <noreply@github.com> on 7/15/2025, 5:04:57 PM