Format source with black and add CI to check

[renefritze]

• [ci] add github action
• format with black
• apply pre-commit config

[codecov-commenter]

Codecov Report

Merging #33 (2efbfd9) into master (5cd788d) will not change coverage.
The diff coverage is 57.89%.

@@           Coverage Diff           @@
##           master      #33   +/-   ##
=======================================
  Coverage   70.50%   70.50%           
=======================================
  Files           6        6           
  Lines         834      834           
=======================================
  Hits          588      588           
  Misses        246      246           

Impacted Files	Coverage Δ
pyevtk/evtk.py	97.29% <ø> (ø)
pyevtk/_version.py	41.57% <36.00%> (ø)
pyevtk/__init__.py	100.00% <100.00%> (ø)
pyevtk/hl.py	80.69% <100.00%> (ø)
pyevtk/vtk.py	85.50% <100.00%> (ø)

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