The cron schedule for the consume task to trigger. The format is "minute hour day month day_of_week" Read
- https://github.com/mrmn2/PdfDing/blob/d0f21ec2f9fbee4b1a2f6b7e0e6c7ea7784ab1bc/pdfding/base/task_helpers.py#L5
- https://huey.readthedocs.io/en/latest/api.html#crontab.