Replace deprecated Celery "TaskSet" with "group"
Replace deprecated Celery "TaskSet" with "group"

http://docs.celeryproject.org/en/3.1/internals/deprecation.html#taskset

ministryofjustice/laa-legal-adviser-api,ministryofjustice/laa-legal-adviser-api,ministryofjustice/laa-legal-adviser-api