Updated test URL patterns to use path() and re_path().

tests/admin_custom_urls/urls.py

@@ -1,7 +1,7 @@
-from django.conf.urls import url
+from django.urls import path
 
 from .models import site
 
 urlpatterns = [
-    url(r'^admin/', site.urls),
+    path('admin/', site.urls),
 ]