The ornamental design for a handbag, as shown and described.
FIG. 1 is a front view of a design of a handbag.
FIG. 2 is a back view of the design of the handbag of FIG. 1.
FIG. 3 is a side view of the design of the handbag of FIG. 1.
FIG. 4 is another side view of the design of the handbag of FIG. 1.
FIG. 5 is a top view of the design of the handbag of FIG. 1; and,
FIG. 6 is a bottom view of the design of the handbag of FIG. 1, showing the shoulder strap in an alternate position.
FIG. 6 shows an alternate position of the shoulder strap in the claimed design. The broken lines in the figures and the areas within the broken lines show grayed-out portions of the handbag that form no part of the claimed design.