Move signal import to django.core

oauth2_provider/settings.py

@@ -19,7 +19,7 @@
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
 from django.http import HttpRequest
-from django.test.signals import setting_changed
+from django.core.signals import setting_changed
 from django.urls import reverse
 from django.utils.module_loading import import_string
 from oauthlib.common import Request