Bump pyyaml from 5.1 to 5.4 in /repositories

Bumps [pyyaml](https://github.com/yaml/pyyaml) from 5.1 to 5.4.
- [Release notes](https://github.com/yaml/pyyaml/releases)
- [Changelog](https://github.com/yaml/pyyaml/blob/master/CHANGES)
- [Commits](yaml/pyyaml@5.1...5.4)

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

repositories/requirements-pip.txt

@@ -2,5 +2,5 @@
 six==1.11.0
 addict==2.1.2
 # required by docker/security & deps
-PyYAML==5.1
+PyYAML==5.4