Drop support for EOL Python 2.7 and 3.5

[hugovk]

Fixes https://github.com/jquast/wcwidth/issues/102.

[codecov[bot]]

Codecov Report

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

Comparison is base (b0e4c88) 100.00% compared to head (76e95af) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #117   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            5         5           
  Lines          105        96    -9     
  Branches        25        23    -2     
=========================================
- Hits           105        96    -9     

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[penguinolog]

@jquast can we move forward with it?

[jquast]

Yes, we can move forward with this this week after the next release that includes #120 if there is such sincere interest from so many developers.

Do not mind about bringing the branch up to date, I will do that. Thank you for your effort @hugovk.