The ornamental design for a handbag, as shown and described.
FIG. 1 is a top front perspective view of a handbag showing my new design, in a closed position;
FIG. 2 is a front view of the handbag of FIG. 1, shown in an alternate open position;
FIG. 3 is a back view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view of thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom view thereof.
The evenly dashed broken lines shown in the drawings depict portions of the article that form no part of the claimed invention. The oval-shaped broken lines shown in the drawings depict stitching which forms no part of the claimed invention.