The ornamental design for a handbag, as shown and described.
FIG. 1 is a front perspective view of an alternative embodiment of the handbag shown in FIG. 1;
FIG. 2 is a left side view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a back view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines showing the handles, 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.