Changes to List backups

removed the optional property backups/items/s3_path from the response with the 200 status

added the new pending enum value to the backups/items/status response property for the response status 200

the backups/items/backup_timestamp response's property format changed from date-time to no format for status 200

the backups/items/completed_at response's property format changed from date-time to no format for status 200

the backups/items/expires_at response's property format changed from date-time to no format for status 200

added the optional property backups/items/restorable to the response with the 200 status

added the optional property backups/items/restore_window_start to the response with the 200 status

endpoint added