Bump pyyaml from 5.1.2 to 5.4

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.1.2 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@5.1.2...5.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -21,7 +21,7 @@ SQLAlchemy==1.2.8
 urllib3==1.23
 Werkzeug==0.16.1
 boto3==1.9.169
-PyYAML==5.1.2
+PyYAML==5.4
 Pillow==8.4
 
 # Frozen transitive dependencies: