FFmpeg version was between n6.0 and n6.1 due to some hot fix
for having it compilable on CI. Since n6.1 has been release,
we should update.
Pick-to: 6.7 6.6 6.5
Change-Id: I0d88599be53748eeb038287abe8aad6c0f189933
Reviewed-by: Jøger Hansegård <joger.hansegard@qt.io>
Reviewed-by: Lars Knoll <lars@knoll.priv.no>