The ornamental design for a handbag, as shown and described.
FIG. 1 is a first perspective view of a handbag showing my new design, with a strap shown in ghost for context;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view of view thereof, where the strap is not shown for visual clarity;
FIG. 4 is a top view thereof, where the strap is not shown for visual clarity;
FIG. 5 is right side view thereof and the left side view is a mirror image of this view, where the strap is not shown for visual clarity;
FIG. 6 is a rear view thereof, where the strap is not shown for visual clarity; and,
FIG. 7 is a bottom view thereof, where the strap is not shown for visual clarity.
The strap depicted and the front flap edge depicted in ghost are not considered part of the inventive design. Dashed lines associated with the edges of the handbag denote stitching and forms part of the claimed design.