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>

requirements/prod.txt

@@ -1,3 +1,3 @@
 panini==0.2.3
-PyYAML==5.1.2
+PyYAML==5.4
 python-dotenv==0.17.0