update python annotations

[NicholasTanz]

Description of the changes being introduced by the pull request:

Fixes #2722

[coveralls]

Pull Request Test Coverage Report for Build 11658095629

Details

• 64 of 64 (100.0%) changed or added relevant lines in 11 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.004%) to 96.61%

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Totals
Change from base Build 11568736074:	0.004%
Covered Lines:	1572
Relevant Lines:	1609

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💛 - Coveralls

[NicholasTanz]

Hi @jku, when you have a moment, could you take a look at this PR. thanks

[jku]

Sorry, I've been distracted. This seems good but I'll take a closer look this week.

Maybe I'll also check with some downstream users if bumping minimum python is ok with them or if we need to still wait a bit before merging...

[NicholasTanz]

No worries, thank you for reviewing my PRs! Let me know if there's anything I can do to help

[kairoaraujo]

Thank you @NicholasTanz for the PR

LGTM (it was on my TODO list too)

I will let @jku look at it before I merge it.

[jku]

Thanks a lot, sorry for delays.

I might still add a from __future__ import annotations before next release (since it would not break compat with 3.8 and will give us even more nice annotations from 3.10) but I think this PR is good either way