[3.12] gh-111784: Fix two segfaults in the elementtree module (GH-113405) (GH-113446)

[3.12] gh-111784: Fix two segfaults in the elementtree module (GH-113405) (GH-113446)

First fix resolve situation when pyexpat module (which contains expat_CAPI
capsule) deallocates before _elementtree, so we need to hold a strong
reference to pyexpat module to.

Second fix resolve situation when module state is deallocated before
deallocation of XMLParser instances, which uses module state to clear
some stuff.
(cherry picked from commit 894f0e573d9eb49cd5864c44328f10a731852dab)

Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>