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](https://github.com/yaml/pyyaml/compare/5.3.1...5.4)

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

requirements.txt

@@ -22,7 +22,7 @@ Pillow==7.1.2
 psutil==5.7.2
 pyparsing==2.4.7
 pytz==2020.1
-PyYAML==5.3.1
+PyYAML==5.4
 six==1.14.0
 sqlparse==0.3.1
 tzlocal==2.1