The ornamental design for a sidingpanel, as shown and described.
FIG. 1 is a top perspective view of a siding panel embodying 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 side view thereof, the right side view being a mirror image;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines illustrate portions of the siding panel that form no part of the claimed design. However, in embodiments other than those illustrated, any lines that are currently illustrated as broken may be redrawn as solid lines, and any lines that are currently illustrated as solid may be redrawn as broken lines. Any surface that is currently claimed can be disclaimed and any surface that is currently disclaimed can be claimed. The scope of the present disclosure encompasses all lines illustrated, whether broken or solid.