The ornamental design for a waistband for pants, as shown and described.
FIG. 1 is a front perspective view of a waistband for pants showing my new design;
FIG. 2 is an enlarged front view thereof; and,
FIG. 3 is an enlarged rear view thereof.
The broken line showing of pants is included for the purpose of illustrating an environment of the article and forms no part of the claimed design.
The broken line showing of stitching on the waistband is for the purpose of illustrating portions of the article that form a part of the claimed design.