The ornamental design for a lighter, as shown and described.
FIG. 1 is a front perspective view of a lighter, showing my new design;
FIG. 2 is a side view of the lighter shown in FIG. 1;
FIG. 3 is a front view of the lighter shown in FIG. 1;
FIG. 4 is a rear view of the lighter shown in FIG. 1;
FIG. 5 is a top view of the lighter shown in FIG. 1; and,
FIG. 6 is a bottom view of the lighter shown in FIG. 1.
The broken lines showing interior features within the two front, top openings of FIG. 1 and the broken lines showing a portion of the bottom view of the lighter in FIG. 6 form no part of the claimed design.