We claim the ornamental design for a hitch pin, as shown and described.
FIG. 1 is a front perspective view of a hitch pin;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings comprise contour lines and form no part of the claimed design.