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 an enlarged second perspective view thereof in an open configuration;
FIG. 3 is a front view of view thereof, where the strap is not shown for visual clarity, and the back view is a mirror image of this view;
FIG. 4 is a left side view thereof and the right side view is a mirror image of this view;
FIG. 5 is a bottom view thereof, where the strap is not shown for visual clarity; and,
FIG. 6 is a top view thereof, where the strap is not shown for visual clarity.
The dot-dashed broken lines showing a strap are for the purposes of illustrating environment and form no part of the claimed design. The smaller dashed lines on the edges of the handbag denote stitching and are part of the claimed design.