django_lightweight_queue.KeyErrorMiddleware class missing 'ident' keyword

The [`django_lightweight_queue.KeyErrorMiddleware`](https://github.com/keyerror/django-keyerror/blob/master/django_keyerror/django_lightweight_queue.py) class uses the `QueueError` helper but fails to pass it an `ident`. Since no default is provided this means that it will error when it fires.