python310Packages.django-sites: mark broken with django_4

Uses API functions deprecated in Django 3.0 and removed in 4.0.

pkgs/development/python-modules/django-sites/default.nix

···
     description = "Alternative implementation of django sites framework";
     homepage = "https://github.com/niwinz/django-sites";
     license = lib.licenses.bsd3;
+    # has not been updated for django>=4.0
+    broken = lib.versionAtLeast django.version "4";
   };
 }