Hangs when waiting on a group of actors.
Hello, This example:
```python
url = "postgresql://postgres:postgres@localhost/postgres"
backend = dramatiq_pg.PostgresBackend(url=url)
broker = StubBroker(middleware=[m() for m in itertools.islice(default_middleware, 1, None)]) # No Prometheus.
broker.emit_after("process_boot")
broker.add_middleware(Results(backend=backend))
broker.add_middleware(CurrentMessage())
dramatiq.set_broker(broker)
broker.flush_all()
worker = dramatiq.Worker(broker)
worker.start()
@dramatiq.actor(store_results=True)
def actor():
actor.logger.info("message: %s", CurrentMessage.get_current_message())
return "YAY"
group = dramatiq.group(actor.message() for _ in range(5)).run()
group.wait()
worker.join()
worker.stop()
broker.close()
```
runs all actors and then hangs until I Ctrl-C the process. The traceback then is:
```
File "/path/to/.venv/lib/python3.10/site-packages/dramatiq_pg/results.py", line 57, in get_result
notifies = wait_for_notifies(curs.connection, timeout=timeout)
File "/path/to/.venv/lib/python3.10/site-packages/dramatiq_pg/utils.py", line 174, in wait_for_notifies
rlist, *_ = select.select([conn], [], [], timeout)
KeyboardInterrupt
```
Please let me know if you can reproduce this? Am I missing something in my setup?
issue