[3.14] gh-134160: Use PyModuleDef.m_free in the example module xxlimited (GH-135174) (GH-135213)

gh-134160: Use PyModuleDef.m_free in the example module xxlimited (GH-135174)
(cherry picked from commit 1adca08d658ee2d520f3193960eaf3ae2ead1cef)

Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: neonene <53406459+neonene@users.noreply.github.com>