Update Django.json. Python version should be 3.9

Redhat end of life notice:
https://catalog.redhat.com/software/containers/ubi8/python-39/6065b24eb92fbda3a4c65d8f

openshift/templates/django-postgresql.json

@@ -422,7 +422,7 @@
       "name": "PYTHON_VERSION",
       "displayName": "Version of Python Image",
       "description": "Version of Python image to be used (3.6-ubi8, 3.8-ubi7, 3.8-ubi8, or latest).",
-      "value": "3.8-ubi8",
+      "value": "3.9",
       "required": true
     },
     {