Streamline CI

[vyasr]

This PR streamlines CI, which is many years out of date with best practices and the current CI infrastructure.

[codecov]

Codecov Report

Merging #37 (736e77f) into master (44eb41e) will decrease coverage by 0.40%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #37      +/-   ##
==========================================
- Coverage   89.62%   89.21%   -0.41%     
==========================================
  Files           6        7       +1     
  Lines         607      612       +5     
  Branches       69       69              
==========================================
+ Hits          544      546       +2     
- Misses         40       42       +2     
- Partials       23       24       +1     

Impacted Files	Coverage Δ
rowan/functions.py	98.53% <ø> (ø)
rowan/mapping/__init__.py	65.11% <0.00%> (-1.75%)	⬇️
rowan/__init__.py	100.00% <0.00%> (ø)

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