Merge pull request #1352 from VWS-Python/dependabot/pip/pyyaml-5.4

Bump pyyaml from 5.3.1 to 5.4

Author: adamtheturtle

dev-requirements.txt

@@ -1,7 +1,7 @@
 # We use dev-requirements.txt instead of just declaring the requirements in
 # the setup function because Read The Docs needs a requirements file.
 black==20.8b1
-PyYAML==5.3.1
+PyYAML==5.4
 Pygments==2.7.4
 Sphinx-Substitution-Extensions==2020.9.30.0
 Sphinx==3.4.3