Django 4.0 compatability

[Brady Moe]

When trying to upgrade our project to Django 4.X we're getting errors around importing url from django.conf.urls which is being imported in the admin view set for wagtail transfer.

There may be other issues with Django 4.0 as well, but that was the first I came across when doing the upgrade.

[Matt Westcott]

Thanks for reporting! This is fixed on main by #104 - will get a new release out with this and other fixes.