⬆️ 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-dev.txt

@@ -54,7 +54,7 @@ pyparsing==2.4.7
     # via packaging
 python-coveralls==2.9.3
     # via -r requirements-dev.in
-pyyaml==5.1.2
+pyyaml==5.4
     # via
     #   -r requirements-dev.in
     #   detect-secrets