Notable changes:
* deps.qt: Remove Qt 5 builds
* deps.qt: Update Qt 6 build scripts
* deps.ffmpeg: Update dependencies for OBS CMake 3.0 upgrade
* deps.windows: Update dependencies for OBS CMake 3.0 upgrade
No dependency versions have changed.
This update is to unblock work on the Windows "CMake 3.0" upgrade and
dropping Qt 5 support.