tests/vm: add py310-expat to NetBSD

tests/vm: add py310-expat to NetBSD

NetBSD cannot successfully run "ensurepip" without access to the pyexpat
module, which NetBSD debundles. Like the Debian patch, it would be
strictly faster long term to install pip/setuptools, and I recommend
developers at their workstations take that approach instead.

For the purposes of a throwaway VM, there's not really a speed
difference for who is responsible for installing pip; us (needs
py310-pip) or Python (needs py310-expat).

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230511035435.734312-14-jsnow@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>