I claim the ornamental design for a handbag, as shown and described.
FIG. 1 is a top, front, and right side perspective view of an ornamental design for a handbag;
FIG. 2 is a front side elevational view thereof;
FIG. 3 is a rear side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a perspective view of an interior of the handbag.
The heavier broken lines showing stitching and the lighter broken lines showing portions of the handbag are for the purposes of illustrating environment and form no part of the claimed design.