Bump pyyaml from 5.3.1 to 5.4

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.3.1 to 5.4. - [Release notes](https://github.com/yaml/pyyaml/releases) - [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES) - [Commits](yaml/pyyaml@5.3.1...5.4) Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -42,7 +42,7 @@ Pygments==2.6.1
 pykube-ng==20.5.0
 python-dateutil==2.8.1
 pytz==2020.1
-PyYAML==5.3.1
+PyYAML==5.4
 redis==3.5.3
 requests==2.23.0
 requests-oauthlib==1.3.0