tests: Fix root uid check in test-commit-sign.sh
tests: Fix root uid check in test-commit-sign.sh

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