I claim the ornamental design for a dog harness, as shown and described.
FIG. 1 is a top, front, right Perspective view of a dog harness showing my new design;
FIG. 2 is a Front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a Top plan view thereof;
FIG. 5 is a Bottom plan view thereof;
FIG. 6 is a Right-side elevation view thereof; and,
FIG. 7 is a Left-side elevation view thereof.
The broken lines are for the purpose of illustrating portions of the article that form no part of the claim and showcased the stitching on the product.