Release of #1700. The following lines need to be added to posthog/celery.py to release PR. Deliberately excluded to manually test the PR without sending everyone an email.

```python
# inside setup_periodic_tasks
sender.add_periodic_task(
    crontab(day_of_week="mon"), task_weekly_email_report.s(),
)

# bottom of file
@app.task
def task_weekly_email_report(self):
    from posthog.tasks.email import send_weekly_email_report

    send_weekly_email_report()
```
posthog/celery.py
redis_instance.set("POSTHOG_HEARTBEAT", int(time.time()))
@app.task
def redis_celery_queue_depth():
    try:
        g = statsd.Gauge("%s_posthog_celery" % (settings.STATSD_PREFIX,))
        llen = redis_instance.llen("celery")
        g.send("queue_depth", llen)
    except:
        
        
        return
@app.task
def update_event_partitions():