[3.13] gh-116510: Fix crash during sub-interpreter shutdown (gh-124645) (#124649)

gh-116510: Fix crash during sub-interpreter shutdown (gh-124645)

Fix a bug that can cause a crash when sub-interpreters use "basic"
single-phase extension modules.  Shared objects could refer to PyGC_Head
nodes that had been freed as part of interpreter shutdown.
(cherry picked from commit 6f9525dd3f0ef5809106ca0923a7512d666a04bb)

Co-authored-by: Neil Schemenauer <nas-github@arctrix.com>