Merge pull request #276 from johnwheeler/dependabot/pip/pyyaml-5.4

Bump pyyaml from 3.12 to 5.4

Author: johnwheeler

requirements.txt

@@ -2,6 +2,6 @@ aniso8601==1.2.0
 Flask==1.1.1
 cryptography==2.1.4
 pyOpenSSL==17.0.0
-PyYAML==3.12
+PyYAML==5.4
 six==1.11.0
 Werkzeug==0.16.1