Upgrade pylint/pylint-test and address variety of pylint issues

[dermotduffy]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bf432a2) 100.00% compared to head (ff24563) 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##            master      #562    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           15        15            
  Lines         2746      1883   -863     
==========================================
- Hits          2746      1883   -863     

Files	Coverage Δ
custom_components/frigate/__init__.py	100.00% <100.00%> (ø)
custom_components/frigate/camera.py	100.00% <100.00%> (ø)
custom_components/frigate/config_flow.py	100.00% <ø> (ø)
custom_components/frigate/const.py	100.00% <ø> (ø)
custom_components/frigate/diagnostics.py	100.00% <100.00%> (ø)
custom_components/frigate/media_source.py	100.00% <100.00%> (ø)
custom_components/frigate/update.py	100.00% <100.00%> (ø)

... and 6 files with indirect coverage changes

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