I claim the ornamental design for a pet harness, as shown and described.
FIG. 1 is a perspective view of a pet harness, showing my new design in a fitted configuration on a dog;
FIG. 2 is a top front left perspective view of the design of FIG. 1, illustrated in an opened and flattened configuration;
FIG. 3 is a left-side elevational view of FIG. 2;
FIG. 4 is a right-side elevational view of FIG. 2;
FIG. 5 is a front elevational view of FIG. 2;
FIG. 6 is a rear elevational view of FIG. 2;
FIG. 7 is a top plan view of FIG. 2; and,
FIG. 8 is a bottom plan view of FIG. 2.
The broken line showing of a dog in FIG. 1 depicts environmental subject matter and forms no part of the claimed design. The broken lines on the harness in FIGS. 1 through 8 represent stitching, and are part of the claimed design.