Updated User Agent for File Ingestion

Starting July 21st, we will be using curl/7.43.0 (Mux) as the user agent when retrieving files for ingestion. This change affects all file retrieval operations for VOD assets. This user agent does not reflect our specific software or version, but ensures compatibility with most file servers. If you have security rules or monitoring based on user agent strings, you may need to update your configurations to allow this new user agent.