Ubuntu 18.04 VM tests

[John Snow]

Hi Alex:

The Ubuntu 18.04 image is by now quite old and we could move our
support forward to Ubuntu 20.04. I have an interest in doing so in
order to avoid a version of pip that is old enough as to cause
problems for some Python work I am attempting to do in order to split
the QMP library fully out of the qemu.git tree.

However, it looks like Ubuntu 20.04 does not have equivalent i386
builds, so I can't just do a drop-and-replace. Do we need a
replacement i386 guest of some sort?

Looks like Fedora dropped i686 some time ago, debian might be our best bet?

--js