tests: Restore accidentally deleted Makefile bit
tests: Restore accidentally deleted Makefile bit

Not sure how this got deleted...

GNOME/ostree,sujitfulse/ostree,leandrosansilva/ostree,resin-io/ostree,gatispaeglis/ostree,GNOME/ostree,sujitfulse/ostree,GNOME/ostree,resin-io/ostree,resin-io/ostree,GNOME/ostree,sujitfulse/ostree,resin-io/ostree,leandrosansilva/ostree,gatispaeglis/ostree,GNOME/ostree,resin-io/ostree,gatispaeglis/ostree,gatispaeglis/ostree,leandrosansilva/ostree,leandrosansilva/ostree,sujitfulse/ostree,gatispaeglis/ostree,sujitfulse/ostree,leandrosansilva/ostree,gatispaeglis/ostree