Bump pyaml from 15.8.2 to 20.4.0 (#486)

Bumps [pyaml](https://github.com/mk-fg/pretty-yaml) from 15.8.2 to 20.4.0.
- [Release notes](https://github.com/mk-fg/pretty-yaml/releases)
- [Commits](https://github.com/mk-fg/pretty-yaml/commits)

Signed-off-by: dependabot-preview[bot] <[email protected]>

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

Author: dependabot-preview[bot]

Pipfile

@@ -20,7 +20,7 @@ boto3 = ">=1.4.4"
 click = "==7.1.2"
 docutils = "*"
 jmespath = "==0.10.0"
-pyaml = "==15.8.2"
+pyaml = "==20.4.0"
 python-dateutil = "==2.8.1"
 PyYAML = "==5.3.1"