Vendored typing_extensions package is broken with more recent python versions

[jdm]

Servo relies on Python 3.11, and we're running into https://stackoverflow.com/questions/77074676/importerror-cannot-import-name-deprecated-from-typing-extensions when we try to run any wdspec tests. I've verified that installing the requirements from

wpt/tools/requirements_mypy.txt

Line 14 in a23771c

typing_extensions==4.12.2

makes the problem disappear if we also remove typing_extensions from localpaths.py. I can't actually figure out a way to avoid the vendored copy that I can upstream, though. Is there some way to update the vendored copy instead?