Add regex stubs

[jpy-git]

This PR closes #6710.

Aim is to provide typing stubs for the regex package.
This regex implementation is backwards-compatible with the standard 're' module, but offers additional functionality.
Github: https://github.com/mrabarnett/mrab-regex
PyPI: https://pypi.org/project/regex/

I'm opening this as a draft as I have a couple questions about how to reference types for classes defined in C code (will annotate the PR with the questions). Any help/suggestions are greatly appreciated 😄

[jpy-git]

Some direction on these points (plus any general improvements) would be really appreciated, thanks! 😄

[AlexWaygood]

With the latest mypy release, we no longer need uppercase Tuple (and attempting to import it will cause CI to fail after the changes to check_new_syntax that I introduced in #6717 🙂)

[jpy-git]

This should be ready for review now 😄

[LeeeeT]

Thank you so much! Your PR is just in time 🚀🚀🚀

[Akuli]

Thanks!

[jpy-git]

Awesome, thanks @Akuli and @AlexWaygood for the great reviews 😄

[richardjharris]

Is this missing __getitem__? After updating some modules I now get hundreds of "__getitem__" method not defined on type "Match[str]" errors.

[srittau]

I'm not using regex and have not investigated, but this seems likely. re.Match (or rather typing.Match) also has a __getitem__() field. Cc @jpy-git

[jpy-git]

Makes sense, will make a PR 👍