Update tox to 3.11.1

[pyup-bot]

This PR updates tox from 3.8.6 to 3.11.1.

The bot wasn't able to find a changelog for this release. Got an idea?

Links

• PyPI: https://pypi.org/project/tox
• Docs: http://tox.readthedocs.org

[codecov]

Codecov Report

Merging #73 into development will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           development     #73   +/-   ##
===========================================
  Coverage         93.6%   93.6%           
===========================================
  Files               41      41           
  Lines             3067    3067           
===========================================
  Hits              2871    2871           
  Misses             196     196

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[coveralls]

Coverage remained the same at 93.739% when pulling ab8a73a on pyup-update-tox-3.8.6-to-3.11.1 into 189837d on development.