We claim the ornamental design for a light source, as shown and described.
FIG. 1 is a front view of an embodiment of the claimed design;
FIG. 2 is a left side view of the embodiment of FIG. 1;
FIG. 3 is a right side view of the embodiment of FIG. 1;
FIG. 4 is a top view of the embodiment of FIG. 1;
FIG. 5 is a rear view of the embodiment of FIG. 1;
FIG. 6 is a front, top perspective view of the embodiment of FIG. 1; and,
FIG. 7 is a rear, bottom perspective view of the embodiment of FIG. 1.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the drawings are included for the purpose of illustrating subject matter that forms no part of the claimed design.