Make sure enum is part of the setup.py

[hunterhector]

This PR fixes #851.

Description of changes

Added enum34 in setup.py.

[codecov]

Codecov Report

Merging #852 (ec04821) into master (8b233e4) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #852   +/-   ##
=======================================
  Coverage   80.73%   80.73%           
=======================================
  Files         254      254           
  Lines       19361    19361           
=======================================
  Hits        15632    15632           
  Misses       3729     3729           

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