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.txt

@@ -34,7 +34,7 @@ sshtunnel==0.1.3
 twisted==19.7.0
 validators==0.12.0
 xmltodict==0.11.0
-pyYAML==5.3.1
+pyYAML==5.4
 typing-extensions==3.7.4.3
 
 git+https://github.com/couchbaselabs/mc_bin_client.git@magma#egg=mc_bin_client