Use ruff for formatting and linting

[johannaengland]

And get rid of MegaLinter.

Best reviewed commit by commit.

[github-actions]

Test results

   12 files     12 suites   11m 36s ⏱️
2 194 tests 2 194 ✅ 0 💤 0 ❌
6 057 runs  6 057 ✅ 0 💤 0 ❌

Results for commit f64f89a.

♻️ This comment has been updated with latest results.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[lunkwill42]

Well would you look at that. Ruff even fixed the annoying string-concatenation-after-reformatting issues that Black wouldn't.

Also nice to get rid of all of those old u"" strings from Python 2 :-)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 0.00%. Comparing base (6fdf19a) to head (f64f89a).
Report is 8 commits behind head on master.

Additional details and impacted files

@@      Coverage Diff       @@
##   master   #3370   +/-   ##
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