GitLab

Summary:
Follow up of  https://github.com/pytorch/audio/pull/3455

FFMPEG_VERSION env ver is not defined in existing CI jobs.

Pull Request resolved: https://github.com/pytorch/audio/pull/3459

Reviewed By: atalman

Differential Revision: D47249074

Pulled By: mthrok

fbshipit-source-id: 20f82d749adef5f45a984ab8125592ef36279e94