fix typing-extensions stubs shadowing typing_extensions

[chdsbd]

It's not possible to use stubs that depend on types-typing-extensions because mypy doesn't allow stubs to override typing-extensions.

The solution is to require typing-extensions instead of types-typing-extensions since mypy and pyright have built in types for this package.

fixes #5065

[chdsbd]

I wasn't sure how to handle this lint.

[chdsbd]

I tested and the stubs uploader doesn't like this yet. nvm

[chdsbd]

I think we may need to update https://github.com/typeshed-internal/stub_uploader/blob/c8c05468be59da2dce0914be3f36d8415dd679da/scripts/build_wheel.py nvm, this change seems to work.

[chdsbd]

I think we may want to disallow types-typing-extensions.

[chdsbd]

@srittau I wasn't sure which core team member to ping, but can I get a review on this? No rush.

[hauntsaninja]

I don't know that this is the right fix. The proximate cause of your issue is that mypy hasn't released a version that supports modularised typeshed; if you use mypy master I believe things should work for the issue you filed.

I'd actually be pretty in favour of pretending typing-extensions is a stdlib module (and I think there are a couple good potential reasons to do this).

[chdsbd]

@hauntsaninja Should I close this PR and wait for mypy to release? Or can we merge this change?

[JukkaL]

Let's wait for the mypy release and see if there still is an issue.

[hauntsaninja]

Obviated by #5233