The ornamental design for a luggage, as shown and described.
FIG. 1 shows a front perspective view of a piece of luggage;
FIG. 2 shows a front elevation view of the piece of luggage of FIG. 1;
FIG. 3 shows a rear elevation view of the piece of luggage of FIG. 1;
FIG. 4 shows a right elevation view of the piece of luggage of FIG. 1;
FIG. 5 shows a left elevation view of the piece of luggage of FIG. 1;
FIG. 6 shows a top view of the piece of luggage of FIG. 1; and,
FIG. 7 shows a bottom view of the piece of luggage of FIG. 1.
The broken lines in FIGS. 1-7 illustrate portions of the piece of luggage that form no part of the claimed design. The dash-dot lines in FIGS. 2 and 7 illustrate a boundary and form no part of the claimed design.