post https://test.billing.gg/api/v1/order_checkouts/
Renew a custom checkout for an iframe integration
If you are integrating the BillPro iframe into your website, the checkout expires after 25 minutes. Use the Renew Checkout request to renew the checkout for an order.
If you use BillPro's built-in checkout, it automatically renews when the user clicks on the link, and you do not need to use this request.