[html.parser] Fix stubtest for later patch releases

[donbarbos]

See python/cpython#118350 backports

[donbarbos]

Hmm, this error didn’t occur on main branch and previous commits. Looks like a false positive but can't figure out why

And I still see this method in source code: https://github.com/python/cpython/blob/3.9/Lib/importlib/_bootstrap_external.py#L1453

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[donbarbos]

The error related to find_distributions method has resurfaced in the main branch. Maybe this PR somehow influenced it, though the issue behaves inconsistently: sometimes it shows up, sometimes it doesn’t.