Move tests jobs to run under macos-12

[Itxaka]

Looks like macos-10.15 is being phased out on August so on some dates, like today, all jobs run on those machines will fail as a way to raise awareness.

That basically blocks us for the whole duration so we should move to macos-12 asap. Virtual box which was not available on macos-11 is now available in the macos-12 image so there should be no blockers to move into this.