text: Title: Task Execution API: Implement default version handling for no header
  Body: Task Execution API versioning was added in https://github.com/apache/airflow/pull/47951 via [Cadwyn](https://github.com/zmievsa/cadwyn). 
  
  As a follow-up we should Implement default version handling for no header since it isn't available out of the box. So if a version isn't provided, we default it to latest.
  