Replace $order->get_id() with $order->get_order_number()

[Željan Topić]

[https://bookingwp.com/forums/topic/problem-to-edit-booking-time-in-backend/](https://bookingwp.com/forums/topic/problem-to-edit-booking-time-in-backend/)

[Željan Topić]

Fixed with 4.5.4