tests: Add test for GIRepository.UnionInfo.get_size()
tests: Add test for GIRepository.UnionInfo.get_size()

https://bugzilla.gnome.org/show_bug.cgi?id=745362
sfeltman/pygobject,pexip/pygobject,pexip/pygobject,sfeltman/pygobject,sfeltman/pygobject,GNOME/pygobject,pexip/pygobject,GNOME/pygobject,GNOME/pygobject