Add pre-commit-config, run black, isort, ...

[dweindl]

Relevant changes are all in .pre-commit-config.yaml, the rest is auto-formatting by isort/black

[codecov-commenter]

Codecov Report

Merging #225 (841aa76) into develop (e54bd82) will decrease coverage by 0.04%.
The diff coverage is 77.88%.

@@             Coverage Diff             @@
##           develop     #225      +/-   ##
===========================================
- Coverage    76.38%   76.34%   -0.04%     
===========================================
  Files           34       34              
  Lines         3180     3179       -1     
  Branches       771      771              
===========================================
- Hits          2429     2427       -2     
- Misses         552      553       +1     
  Partials       199      199              

Files Changed	Coverage Δ
petab/petablint.py	0.00% <0.00%> (ø)
petab/visualize/cli.py	0.00% <0.00%> (ø)
petab/visualize/lint.py	52.77% <12.50%> (ø)
petab/models/pysb_model.py	60.80% <50.00%> (ø)
petab/simplify.py	66.66% <50.00%> (ø)
petab/sbml.py	69.23% <53.33%> (ø)
petab/visualize/plot_data_and_simulation.py	76.66% <63.63%> (ø)
petab/parameter_mapping.py	66.32% <64.00%> (ø)
petab/problem.py	64.89% <66.66%> (ø)
petab/visualize/helper_functions.py	78.12% <66.66%> (ø)
... and 23 more