Add docstring linting via ruff

[cchwala]

This PR does the following

• [x] add numpy docstring format linting via ruff
• [x] add some other recommended ruff settings ("E" # style errors, "W" # style warnings, "F" # flakes, "U" pyupgrade)
• [x] set line length to 88, the default of black
• [x] adjust code and docstrings to new linting rules

Checklist:

• [x] closes #8
• [ ] Tests added and passed if fixing a bug or adding a new feature
• [x] All code checks from pre-commit passed
• [x] Added an entry in the CHANGELOG.md file

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (e965b76) to head (29a54c2). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #18 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 2 2 Lines 23 23 ========================================= Hits 23 23 ```

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