[pygobject] (5 commits) Non-fast-forward update to branch wip/mschraal/gtk4-container-removal

[Christoph Reiter <creiter src gnome org>]

The branch 'wip/mschraal/gtk4-container-removal' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  d897a6a... gtk overrides: Remove Container use for GTK4

Commits added to the branch:

  4208cf1... Revert the dependency bump for libffi (*)
  b991b9d... CI: test with Python 3.9 (*)
  2913e72... Don't call PyEval_InitThreads() with Python 3.9+ (*)
  c945c99... Replace PyUnicode_GET_SIZE() usage with PyUnicode_GET_LENGT (*)
  5657e62... gtk overrides: Remove Container use for GTK4

(*) This commit already existed in another branch; no separate mail sent