The ornamental design for a weightplate, as shown and described.
FIG. 1 is a top, front, perspective view of a weight plate showing our new design;
FIG. 2 is a bottom, front, perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The uneven-length broken lines represent boundaries of the claimed design and form no part thereof. The even-length broken lines depicting the remainder of the weight plate show features that form no part of the claimed design. The even-length broken lines showing lettering form no part of the claimed design.