The ornamented 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 top plan view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is a top plan view in an alternate configuration, where the bag is open.
The dash-dash broken lines shown represent unclaimed subject matter and form no part of the claimed design. The dot-dash broken lines shown in the drawings represent an unclaimed boundary between claimed and unclaimed surfaces.