Support autoreload of `db_worker`

[daniboygg]

I was testing this package and created a Django admin action to trigger the enqueue of a task. After getting everything working, I changed the code to modify the task result. However, after queuing the task, I still got the old result.

My guess is that when running the db_worker, you need to restart the command if you change the code. Is this expected behavior? I was surprised because I'm used to Django's runserver restarting on code changes. Could be a good idea to document this in the README?