The ornamental designs for a “panel light,” as shown and described.
FIG. 1 is a first perspective view of a panel light;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. The broken lines in the figures depict portions of the panel light that form no part of the claimed design.