The ornamental design for a packingpanel, as shown and described.
FIG. 1 is a front perspective view of the packing panel in accordance with my design;
FIG. 2 is a top view of the packing panel of FIG. 1;
FIG. 3 is a first end view of the packing panel of FIG. 1;
FIG. 4 is a second end view of the packing panel of FIG. 1;
FIG. 5 is a first side view of the packing panel of FIG. 1;
FIG. 6 is a second side view of the packing panel of FIG. 1; and,
FIG. 7 is a back view of the packing panel of FIG. 1.
The broken away symbols in the drawings indicate the appearance of any portion of the article between the break lines forms no part of the claimed design.