[fix] support django-4.1

tests/testapp/urls.py

@@ -14,8 +14,8 @@ Including another URLconf
     2. Add a URL to urlpatterns:  path('blog/', include('blog.urls'))
 """
 from django.contrib import admin
-from django.conf.urls import url
+from django.urls import re_path
 
 urlpatterns = [
-    url(r'^admin/', admin.site.urls),
+    re_path(r'^admin/', admin.site.urls),
 ]