Merge pull request #1180 from adamtheturtle/dependabot/pip/pyyaml-5.3.1

Bump pyyaml from 5.3 to 5.3.1

Author: adamtheturtle

dev-requirements.txt

@@ -1,6 +1,6 @@
 # We use dev-requirements.txt instead of just declaring the requirements here
 # because Read The Docs needs a requirements file.
-PyYAML==5.3
+PyYAML==5.3.1
 Pygments==2.6.1
 Sphinx-Substitution-Extensions==2020.2.21.0
 Sphinx==2.4.4