trivial: Allow 'license' for the deprecated fallback tag
trivial: Allow 'license' for the deprecated fallback tag

Two applications have done this now, so just do the easy thing and accept either.

hughsie/appstream-glib,superm1/appstream-glib,ximion/appstream-glib,superm1/appstream-glib,ximion/appstream-glib,mitya57/appstream-glib,ikeydoherty/appstream-glib,hughsie/appstream-glib,mitya57/appstream-glib,hughsie/appstream-glib,kalev/appstream-glib,ximion/appstream-glib,ikeydoherty/appstream-glib,kalev/appstream-glib