The ornamental design for a handbag, as shown and described.
FIG. 1 is a front perspective view of the handbag of the present invention;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIGS. 4 and 5 are side views thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof;
FIG. 8 is a front perspective view thereof with the handbag in a partially open position; and,
FIG. 9 is a rear perspective view thereof with the handbag in a partially open position.
The broken lines inside of the zipper opening in FIGS. 8 and 9 depict boundaries only and form no part of the claimed design; while the remaining broken lines depict environment only and form no part of the claimed design.