Use ruff for our python lints

[jleibs]

Ruff seems likely to be faster and more stable, though it did want to re-sort a lot of our imports.
These mostly seem to make sense, since from the perspective of examples, rerun is just another external dep and should be sorted as such.

$ time just py-lint
black --check --config rerun_py/pyproject.toml --diff examples rerun_py scripts
All done! ✨ 🍰 ✨
80 files would be left unchanged.
blackdoc --check examples rerun_py scripts
All done! ✨ 🍰 ✨
82 files would be left unchanged.
ruff check --config rerun_py/pyproject.toml  examples rerun_py scripts

real    0m0.384s
user    0m1.448s
sys     0m0.236s

And looks to run consistently in CI:

#1377

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I've added a line to CHANGELOG.md (if this is a big enough change to warrant it)

[emilk]

Let's delete .flake8 too

[emilk]

so nice!

[emilk]

niiiice