Update settings.py

This is needed for LB (e.g., traefik) for proxying into nginx
otherwise, get CSRF error
ref: https://stackoverflow.com/questions/27533011/django-csrf-error-casused-by-nginx-x-forwarded-host

resolved by adding USE_X_FORWARDED_HOST using the following similar issue as a reference:
https://github.com/catmaid/CATMAID/issues/1781

installer/roles/image_build/files/settings.py

@@ -85,4 +85,5 @@ DATABASES = {
 if os.getenv("DATABASE_SSLMODE", False):
     DATABASES['default']['OPTIONS'] = {'sslmode': os.getenv("DATABASE_SSLMODE")}
 
+USE_X_FORWARDED_HOST = True
 USE_X_FORWARDED_PORT = True