Format broadbean with ruff

[jenshnielsen]

This replaces darker with the ruff formatter.
I think that by now formatting has become so established that it makes sense to format all our code automatically

[codecov]

Codecov Report

Attention: Patch coverage is 62.62887% with 145 lines in your changes are missing coverage. Please review.

Project coverage is 71.88%. Comparing base (b3ba55d) to head (beb96a7).

Files	Patch %	Lines
src/broadbean/plotting.py	0.00%	75 Missing ⚠️
src/broadbean/sequence.py	76.47%	32 Missing ⚠️
src/broadbean/blueprint.py	78.31%	18 Missing ⚠️
src/broadbean/ripasso.py	57.14%	9 Missing ⚠️
src/broadbean/element.py	87.27%	7 Missing ⚠️
src/broadbean/tools.py	77.77%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #811      +/-   ##
==========================================
- Coverage   72.01%   71.88%   -0.13%     
==========================================
  Files           9        9              
  Lines        1547     1547              
==========================================
- Hits         1114     1112       -2     
- Misses        433      435       +2     

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[astafan8]

Looks good to me!