[3.13] gh-121266: Remove Py_ALWAYS_INLINE in dictobject.c (GH-121493)

[miss-islington]

compare_unicode_generic(), compare_unicode_unicode() and
compare_generic() are callbacks used by do_lookup(). When enabling
assertions, it's not possible to inline these functions.
(cherry picked from commit c5a6b9a)

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

• Issue: always_inline makes build fail with -Og and --without-pydebug #121266