I claim the ornamental design for a pet harness, as shown and described.
FIG. 1 is a top, front, right perspective view of a pet harness, showing my new design in a condition of use.
FIG. 2 is a top, rear, left perspective view thereof.
FIG. 3 is a front elevation view thereof.
FIG. 4 is a left side elevation view thereof.
FIG. 5 is a right side elevation view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
In the drawings, the broken line showing of a dog and harness hardware (ring and webbing fastener) depicts environmental subject matter only and forms no part of the claimed design.