Added comments on why python 3.6 and 3.7 are not tested with django 4 in CI

Author: WisdomPill

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
             redis-version: 'master'
             python-version: '3.10'
 
-        # exclude python 3.6 and 3.7 for django 4.x
+        # exclude python 3.6 and 3.7 for django 4.x as they are not supported see https://docs.djangoproject.com/en/dev/releases/4.0/#python-compatibility
         exclude:
           - django-version: '4.0'
             python-version: '3.6'