Replaced ugettext and ugettext_lazy with gettext and gettext_lazy

ugettext and ugettext_lazy were deprecated in Django 3 and will be
removed in Django 4.

dav_auth/admin.py

@@ -2,7 +2,7 @@ from django.contrib import admin
 from django.contrib.auth.admin import GroupAdmin as _GroupAdmin
 from django.contrib.auth.models import Group
 from django.contrib.auth.models import Permission
-from django.utils.translation import ugettext as _
+from django.utils.translation import gettext as _
 admin.site.unregister(Group)