Update pyyaml to 5.4

[pyup-bot]

This PR updates PyYAML from 3.13 to 5.4.

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

Links

• PyPI: https://pypi.org/project/pyyaml
• Homepage: https://pyyaml.org/

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@97e3944). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #93   +/-   ##
=========================================
  Coverage          ?   43.58%           
=========================================
  Files             ?        7           
  Lines             ?      686           
  Branches          ?      139           
=========================================
  Hits              ?      299           
  Misses            ?      378           
  Partials          ?        9           

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[coveralls]

Coverage decreased (-0.02%) to 39.153% when pulling cc97556 on pyup-update-pyyaml-3.13-to-5.4 into 97e3944 on master.

[pyup-bot]

Closing this in favor of #94