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 elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a bottom view thereof; and,
FIG. 7 is a top view thereof.
The dot-dashed broken lines showing the interior represent the bounds of the claim. The evenly spaced broken lines showing the handle and zipper pull are for the purposes of illustrating environment and form no part of the claimed design. None of the broken lines form part of the claimed design.