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] <[email protected]>

Author: dependabot[bot]

requirements-frozen.txt

@@ -0,0 +1,22 @@
+black==20.8b1
+mypy==0.782
+pre-commit==2.7.1
+click==7.1.2
+mysqlclient==2.0.1
+## The following requirements were added by pip freeze:
+appdirs==1.4.4
+cfgv==3.2.0
+distlib==0.3.1
+filelock==3.0.12
+identify==1.5.3
+mypy-extensions==0.4.3
+nodeenv==1.5.0
+pathspec==0.8.0
+pkg-resources==0.0.0
+PyYAML==5.4
+regex==2020.7.14
+six==1.15.0
+toml==0.10.1
+typed-ast==1.4.1
+typing-extensions==3.7.4.3
+virtualenv==20.0.31