Update setup.cfg

[dwighthubbard]

Update the python_requires.

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.10%. Comparing base (852ceca) to head (7a2501b).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #49      +/-   ##
==========================================
- Coverage   79.32%   79.10%   -0.22%     
==========================================
  Files           6        6              
  Lines         295      292       -3     
  Branches       35       35              
==========================================
- Hits          234      231       -3     
  Misses         47       47              
  Partials       14       14              

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