Create any audio content with a user provided script

Starts a background job to produce an audio file with the provided script segments. The response contains a job_id that can be used to query with the /podcast/{job_id} to query for status. Requires a valid X-API-TOKEN header.

Throws:
- 429 if the user has too many jobs in flight.
- 400 if any voice_id or music_id provided is invalid