Reverts aiofiles back to _typeshed Self

[erwinkinn]

Hello,all.
This PR reverts those changes @AlexWaygood made about five days ago. After that I'd started getting this mypy error:

error: Self? has no attribute "__anext__"  [attr-defined]

A minimal code to reproduce:

async def test_():
    async with aiofiles.open(__file__) as fp:
        async for line in fp:   # <--- error here
            ...

It's quite similar to #5725, but the problem is typing_extensions.Self was not made to support an async iterator protocol.
So I've tried to rollback to an abstract type Self from _typeshed making a hot-hot fix just for now.

I'm not sure, maybe it's better to create an issue at typing_extensions for the occasion...

[Avasam]

Tangiantially related, FWIW, the changes in #9694 added type errors in typeshed's own code, see comment: https://github.com/python/typeshed/pull/9694/files#r1109192407 about usage of int.__new__(...) (for instance at: https://github.com/python/typeshed/blob/main/scripts/stubsabot.py#L37)

Maybe a larger discussion about typing_extensions.Self support is needed.

[erwinkinn]

Yes, maybe u r right. I'm under my way making an issue at typing_extensions at the moment.
I have planned to reference this merge request.

[github-actions]

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

[erwinkinn]

Oh, thanks to bot )) However, it's still on my screen in VS Code (mypy works as a plugin).

As well as at my console...

[erwinkinn]

@Avasam, sorry, I'm not sure I did understand it right. Did you mean a larger discussion about typing_extensions.Self support within the typeshed project? I thought it was about an async iterator protocol support for typing_extensions.Self :) Anyway... Discussion is needed obviously )

[AlexWaygood]

This isn't an issue with typeshed, it's to do with the fact that mypy only recently added support for typing_extensions.Self. It looks like you're not using the latest version of mypy.

I can reproduce this error on mypy 0.991, but not on mypy 1.0. Mypy only added support for typing_extensions.Self in version 1.0, so I'd advise upgrading to the latest mypy if possible. If that's not possible for some reason, then your best bet is to pin your version of types-aiofiles to 22.1.0.7 or lower.