We add some opensuse builds (added to tox.ini in #30619) to GH Actions

Also opensuse/leap:15.3 is available (RC?)

Depends on #30619

CC: @jengelh @dimpase @kliem

Component: porting

Author: Matthias Koeppe

Branch/Commit: 9708864

Reviewer: Jonathan Kliem

Issue created by migration from https://trac.sagemath.org/ticket/29527