Remove support for Python 3.8

[IvanIsCoding]

This is our yearly Python version maintenance. 3.8 reached EOL. I will add the newly released 3.13 in a separate PR to test the wheel release etc.

I profited to update black, ruff and mypy as well. mypy passes without any changes, but there were some minor differences with black and ruff.

[coveralls]

Pull Request Test Coverage Report for Build 11171426645

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 95.816%

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Totals
Change from base Build 11153261135:	0.0%
Covered Lines:	17999
Relevant Lines:	18785

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💛 - Coveralls

[mtreinish]

This lgtm and it looks like is ci passing with the correct python versions. Thanks for doing this.

[mtreinish]

I need to push a PR to update this config with GitHub merge queues we don't need this, and we can only use mergify for automated backporting.

[IvanIsCoding]

Ditto. I actually quite like the GitHub queues, we could move some more expensive checks to the final merge instead of running them each time