Update python setup and codecov actions

[michaelosthege]

Because the codecov action v1 stops working in February 2022.

[codecov-commenter]

Codecov Report

Merging #26 (82d151d) into master (dc5e910) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #26   +/-   ##
=======================================
  Coverage   98.11%   98.11%           
=======================================
  Files           5        5           
  Lines         265      265           
=======================================
  Hits          260      260           
  Misses          5        5           

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