ci(coverage): add coverage to GitHub actions

[jdhughes-dev]

No description provided.

[coveralls]

Coverage decreased (-0.1%) to 61.098% when pulling 1ba412d on jdhughes-usgs:ci-coverage into e8cb2ac on modflowpy:master.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@e8cb2ac). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #61   +/-   ##
=========================================
  Coverage          ?   63.18%           
=========================================
  Files             ?       14           
  Lines             ?     3863           
  Branches          ?        0           
=========================================
  Hits              ?     2441           
  Misses            ?     1422           
  Partials          ?        0           

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