Update pyyaml to 5.4.1

[pyup-bot]

This PR updates PyYAML from 3.12 to 5.4.1.

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-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@6ab31c0). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #453   +/-   ##
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  Coverage          ?   91.07%           
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  Files             ?        4           
  Lines             ?       56           
  Branches          ?        0           
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  Hits              ?       51           
  Misses            ?        5           
  Partials          ?        0           

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[pyup-bot]

Closing this in favor of #543