bugfix: import slipped out of my PR ¯\_(ツ)_/¯

djangoldp_notification/models.py

@@ -11,6 +11,7 @@ from django.db.models.signals import post_save
 from django.dispatch import receiver
 from oidc_provider.models import Token
 from django.urls import NoReverseMatch
+from django.utils.translation import ugettext_lazy as _
 
 from djangoldp.fields import LDPUrlField
 from djangoldp.models import Model