The ornamental design for a handbag, as shown and described.
FIG. 1 is a front perspective view of a handbag;
FIG. 2 is a front view of the handbag shown in FIG. 1;
FIG. 3 is a rear view of the handbag shown in FIG. 1;
FIG. 4 is a left side of the handbag shown in FIG. 1;
FIG. 5 is a right side view of the handbag shown in FIG. 1;
FIG. 6 is a top view of the handbag shown in FIG. 1; and,
FIG. 7 is a bottom view of the handbag shown in FIG. 1.
The broken lines showing the handles, portion of the straps, zippers, zipper pulls, metal clasp, hanging leather tabs and portions of the body of the bag are for the purposes of illustrating environment and forms no part of the claimed design.