I claim the ornamental design for a runner's plaque, as shown and described.
FIG. 1 is a perspective view of a runner's plaque, showing my new design;
FIG. 2 is a front elevational view thereof with some of the environmental matter shown in FIG. 1 removed.
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left-side elevational view thereof, the right-side elevational view being a mirror image thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines showing text, runner's bibs, and side portions of the plaque with hooks in the figures depict environmental matter and form no part of the claimed design.