Bump pyyaml from 5.1 to 5.3.1 (nficano#469)

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.1 to 5.3.1.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@5.1...5.3.1)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

Pipfile

@@ -22,7 +22,7 @@ docutils = "*"
 jmespath = "==0.10.0"
 pyaml = "==15.8.2"
 python-dateutil = "==2.8.1"
-PyYAML = "==5.1"
+PyYAML = "==5.3.1"
 
 [pipenv]
 allow_prereleases = true