Bump ruff to v0.8

[danielhollas]

Builds on top of #6614, which should be reviewed and merged first.

I've pushed this as a separate PR for easier review. Marking this as draft until then.

Most of the changes here come from a new rule RUF022

 unsorted-dunder-all (RUF022)

Derived from the **Ruff-specific rules** linter.

Fix is sometimes available.

## What it does
Checks for `__all__` definitions that are not ordered
according to an "isort-style" sort.

An isort-style sort orders items first according to their casing:
SCREAMING_SNAKE_CASE names (conventionally used for global constants)
come first, followed by CamelCase names (conventionally used for
classes), followed by anything else. Within each category,
a [natural sort](https://en.wikipedia.org/wiki/Natural_sort_order)
is used to order the elements.

[danielhollas]

@unkcpz this is now ready for review

[unkcpz]

Thanks, looks all good!
I remember two weeks ago I sometime to check how to have both isort and ruff for my neovim. Now everything is in ruff!

[danielhollas]

To be clear, ruff was already doing what isort does, i.e. ordering import statements. This new rule that sorts the __all__ = expressions is not implemented in isort (I don't think).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.89%. Comparing base (ef60b66) to head (eb29442).
Report is 152 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6634      +/-   ##
==========================================
+ Coverage   77.51%   77.89%   +0.39%     
==========================================
  Files         560      567       +7     
  Lines       41444    42180     +736     
==========================================
+ Hits        32120    32853     +733     
- Misses       9324     9327       +3     

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