The ornamental design for a lantern, as shown and described.
FIG. 1 is a perspective view of the lantern, showing our new design;
FIG. 2 is an exploded perspective view of FIG. 1;
FIG. 3 is a front elevation view of FIG. 2, the rear elevation view, the right side elevation view and the left side elevation view being a mirror image;
FIG. 4 is a top plan view of FIG. 2; and,
FIG. 5 is a bottom plan view of FIG. 2.
The break lines in FIGS. 1, 2 and 3 are to indicate that the appearance of any portion of the lantern between the break lines forms no part of the claimed design, and the broken lines in FIGS. 1, 2 and 3 represent the portions of the lantern that form no part of the claimed design as well.