* bpo-40548: Always run GitHub action, even on doc PRs (GH-19981)

Always run GitHub action jobs, even on documentation-only pull
requests. So it will be possible to make a GitHub action job, like
the Windows (64-bit) job, mandatory.

(cherry picked from commit 4e363761fc02a89d53aba4382dc451293bd6f0ba)

* bpo-40548: GitHub Action workflow: skip jobs on doc only PRs (GH-19983)

Signed-off-by: Filipe Laíns <lains@archlinux.org>
(cherry picked from commit 75d7257b201a56f950c20cd9f5753a83fff4742b)

* bpo-40548: github actions: pass the changes check on no source changes (GH-20097)

Signed-off-by: Filipe Laíns <lains@archlinux.org>
(cherry picked from commit 6a78589b6b22878491a4b042bb8b3161e1d120f6)

Co-authored-by: Filipe Laíns <filipe.lains@gmail.com>
Co-authored-by: Filipe Laíns <lains@archlinux.org>
(cherry picked from commit 07bd5cf3d9551ae84100e6400836163fcd507f07)

Co-authored-by: Victor Stinner <vstinner@python.org>