fix: lms.startup -> django.setup (#1202)

lms/startup.py performs no logic other than setting up
django, so it is being removed upstream:
openedx/edx-platform#36302

tutor/templates/build/openedx/bin/site-configuration

@@ -1,8 +1,8 @@
 #! /usr/bin/env python3
 import argparse
-import lms.startup
+import django
 
-lms.startup.run()
+django.setup()
 
 from django.conf import settings
 from django.contrib.sites.models import Site