v3.1

• Added /metrics endpoint to expose RQ metrics in Prometheus format. Thanks @terencehonles!
• Added token based authentication for the /metrics and /stats.json endpoints. Thanks @RasmusThing!
• Migrated Django-RQ to use Python's modern packaging standard. Thanks @terencehonles!
• Fixed an issue with setting result_ttl via job decorators. Thanks @Sir-heed!
• Various admin page improvements. Thanks @selwin and @DhavalGojiya!