fix: renamed signals to receivers as per new django-oscar version

ecommerce/extensions/offer/management/commands/remove_partner_offers.py

@@ -8,7 +8,7 @@
 from django.core.management import BaseCommand
 from django.db.models import signals
 from django.template.defaultfilters import pluralize
-from oscar.apps.offer.signals import delete_unused_related_conditions_and_benefits
+from oscar.apps.offer.receivers import delete_unused_related_conditions_and_benefits
 from oscar.core.loading import get_model
 
 from ecommerce.extensions.order.management.commands.prompt import query_yes_no