Make docker build cron once a week and not every hour on Wed (#71255)
Summary:
The many times a day was probably not intentional
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71255
Reviewed By: suo, atalman
Differential Revision: D33559155
Pulled By: janeyx99
fbshipit-source-id: c8703cea6f3188c9bcb0867b895261808d3164ee
