The ornamental design for a publicity vehicle, as shown and described.
FIG. 1 is a right side view of a publicity vehicle showing our new design, the left side view of the publicity vehicle is not included in the drawings because it is an essentially identical mirror image of the right side view;
FIG. 2 is a front view of the publicity vehicle of FIG. 1;
FIG. 3 is a rear view of the publicity vehicle of FIG. 1; and,
FIG. 4 is a top view of the publicity vehicle of FIG. 1.