The ornamental design for a hitchpinretainer, as shown and described.
FIG. 1 is a top perspective view of a hitch pin retainer showing my new design;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left view thereof;
FIG. 6 is a right view thereof;
FIG. 7 is a top view thereof;
FIG. 8 is a bottom view thereof; and,
FIG. 9 is a section view thereof taken along line 9-9 in FIG. 7.
The broken lines illustrate portions of the hitch pin retainer and form no part of the claimed design. The broken lines depicting cut lines in FIG. 7 form no part of the claimed design.