(vlc): conan package depends on testing dependencies

What does this MR do?

Update VLC to 3.0.6-r2 to depends from Qt and FFMpeg of the testing branch.

How to test it?

Build...

Associated Issues/Merge Requests

• Issues

  • Closes #364 (closed)

• Merge requests

  • https://git.ircad.fr/conan/conan-vlc/merge_requests/4