The ornamental design for weighing scale, as shown and described.
FIG. 1 is a perspective view of a weighing scale, with the top and two sides shown, according to an embodiment of the present design;
FIG. 2 is a perspective view of the above embodiment of the scale, with the bottom and two sides shown;
FIG. 3 is a top view of the scale;
FIG. 4 is a bottom view of the scale;
FIG. 5 is a side view of one side of the scale, which is identical to the other side which is parallel thereto; and,
FIG. 6 is a side view of another (adjacent) side of the scale, which is identical to the other side which is parallel thereto.
Aspects that do not form part of the claimed design include the center (circular) portion of the scale feet as shown FIGS. 2, 4, 5 and 6, and the rectangular panel (e.g., compartment for battery or other powering devices), as shown in FIGS. 2 and 4.