YYYY-MM-DD-formatted date when the newly created subscription is scheduled for cancellation.
This date overrides the cancellation date set in the plan configuration.
If the cancellation date is earlier than the end date of a subscription cycle, the subscription stops
at the canceled date and the subscriber is sent a prorated invoice at the beginning of the canceled cycle.
When the subscription plan of the newly created subscription has a fixed number of cycles and the
occurs before the subscription plan expires, the specified
canceled_date sets the date when the subscription
stops through the end of the last cycle.