tests: fix PASSWORD_HASHERS setting to work with RBAC tests (fixes #22199)

tests/settings.py

@@ -1,8 +1,9 @@
 import os
 
-from authentic2.settings import PASSWORD_HASHERS
-
 # use a faster hasing scheme for passwords
+if 'PASSWORD_HASHERS' not in locals():
+    from django.conf.global_settings import PASSWORD_HASHERS
+
 PASSWORD_HASHERS = ('django.contrib.auth.hashers.UnsaltedMD5PasswordHasher',) + PASSWORD_HASHERS
 
 LANGUAGE_CODE = 'en'