Adding KTN and PRN as supported document types

New Feature: You can now use known_traveler_number (a.k.a KTN) and passenger_redress_number (a.k.a PRN) as valid document types when creating flights' orders.

The KTN, also known as the Known Traveller Number, is particularly useful for passengers who want their TSA PreCheck indicator to appear on their boarding pass. And, the PRN, or Passenger Redress Number, is intended for passengers who wish to take advantage of the TSA Secure Flight program.

To determine whether an offer supports the new document types, you can refer to the new field supported_passenger_identity_document_types in the Offer schema. If the document type is listed there, you can provide the document number during the order request.

Deprecation: We’re deprecating the allowed_passenger_identity_document_types in the Offer schema. This field functions similarly to supported_passenger_identity_docyment_types. However, the key difference is that the new attribute will not reject an order with a status 422 if extra document types are included. Instead, the Duffel API will automatically select and send only the documents supported by the airline. The allowed_passenger_identity_document_types field will always return all possible document types for backward compatibility with existing behaviour.