The ornamental design for a handbag, as shown and described.
FIG. 1 is a front perspective view of a handbag showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof; and,
FIG. 6 is a top view thereof.
The broken line showing of the grommets, closure flap, buckle, handles, portions of the handbag, and straps is for illustrative purposes only and forms no part of the claimed design.
The bottom of the handbag is plain and unornamented, and forms no pat of the claimed design.