fix: revert PyYAML version change pending investigation

Author: bodom0015

requirements.txt

@@ -1,7 +1,7 @@
 # Connexion + Swagger tools
 connexion[swagger-ui]==2.7.0
 Werkzeug==2.0.1
-PyYAML==6.0.3
+PyYAML==5.4.1
 prance==0.21.8.0
 Flask-Cors==3.0.10
 flask-sock==0.5.2