old_contents: import django.dispatch
  
  webhook_event = django.dispatch.Signal(providing_args=["event"])
  
new_contents: import django.dispatch
  
  # This signal provides the `event` argument to receivers.
  # See https://github.com/gadventures/django-gapi-hooked#django-signals
  webhook_event = django.dispatch.Signal()
  
subject: Remove deprecated `providing_args` argument to Signal (#24)