[3.13] gh-132674: fix `_hashopenssl.c` compiler warnings on free-threaded build (GH-132675) (#132677)

gh-132674: fix `_hashopenssl.c` compiler warnings on free-threaded build (GH-132675)
(cherry picked from commit 2df0f8804701cc17674e5b4e90499e9fac71d0e1)

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>