[3.13] gh-135607: remove null checking of weakref list in dealloc of extension modules and objects (#135614) (#136126)

gh-135607: remove null checking of weakref list in dealloc of extension modules and objects (#135614)

(cherry picked from commit b1056c2a446b43452e457d5fd5f1bde66afd3883)

Co-authored-by: Xuanteng Huang <44627253+xuantengh@users.noreply.github.com>
Co-authored-by: Kumar Aditya <kumaraditya@python.org>