List openSUSE 42.3 as a supported distro
List openSUSE 42.3 as a supported distro

openSUSE 42.3 is a relatively minor update over 42.2 and I'd
like to maintain it and keep it passing.

Experimental gates are being proposed, once those are passing
(which should be the case with this patch included), we could
enable it as a non-voting gate.

Change-Id: Ia421ada0ed3751c65a2a93a208e3f4a43edf8b16

dtroyer/devstack,group-policy/devstack,dtroyer/devstack,noironetworks/devstack,nawawi/openstack,noironetworks/devstack,openstack-dev/devstack,nawawi/openstack,openstack-dev/devstack,group-policy/devstack