Added support for Concatenate with Ellipsis

[Daraan]

Fixes #110 for Python 3.9-3.10:

An Ellipsis cannot be used with Concatenate as last parameter must be a ParamSpec in Python 3.11 this is allowed, Python 3.10 does not support this.

Does not fix:

• #48 : Using Ellipsis as argument for Callable with a generic..
  • <= 3.9: because of typing.Callable limitations
  • For 3.10 could go back to typing_extentions._ConcatenateGenericAlias but also tricky.
• #110 for Python 3.8 as this is caused by typing.Callable as it does only accepts args that are types, i.e. Ellipsis is not supported.

Changes:

• Changed _concatenate_getitem to reflect the Python3.11 typing module that allows the Ellipsis parameter.
• For Python 3.10 uses typing._ConcatenateGenericAlias and an alternate _concatenate_getitem
• For <=Python 3.9 the typing_extensions._ConcatenateGenericAlias and _concatenate_getitem like before
• Added tests

Python Versions:

• 3.8 not fixable, ok but skipped tests.
• 3.9 ok
  • 3.9.0 ok (locally)
• 3.10 ok
  • 3.10.0 ok (locally)
• 3.11 ok - no backport. One new test for #48 that only runs on 3.11+

---

EDIT: Accounted for changes in Python. 3.9.2 and ~3.10.2, Tests for 3.*.0 should work now.

[ghost]

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[Daraan]

I've made a rework (moved the parts to _create_concatenate_alias) that is now simpler and also works for Python 3.8 and fully solves #110 on the current version range.

[AlexWaygood]

Looks like you might have closed this accidentally. Probably this is something to do with the fact that it was a PR from your fork's main branch. I think it's unfortunately impossible to repair PRs when they get to this state — do you want to recreate the PR using a different branch on your fork? :-)

[Daraan]

Thanks for your kind reply. Yep I've just butchered this 🙈, I am sorry. It's as you assume related to the fork from main ...

[AlexWaygood]

We've all been there, pretty sure I've done it at least once :-)