Running in FreeBSD with vmactions/freebsd-vm

[aantron]

With Travis, Luv previously had a FreeBSD build. GitHub Actions does not offer FreeBSD runners. However, there is vmactions/freebsd-vm which makes this possible. Given that opam offers binary releases for FreeBSD (and OpenBSD), would it be possible and reasonable to support running on FreeBSD with setup-ocaml somehow? I am not sure how this could work, given that GitHub Actions don't seem to compose "into" the VM, but would you be able to look into it?