The ornamental design for a lighting fixture, as shown and described.
FIG. 1 is a fragmentary end view, slightly tilted and showing one end, a portion of the bottom, and a portion of one side of the lighting fixture of my new design;
FIG. 2 is a fragmentary perspective view thereof showing one end, a portion of the bottom, and a portion of one side of the lighting fixture of FIG. 1; and,
FIG. 3 is a longitudinal side elevation thereof showing the opposite side of the lighting fixture of FIG. 1.
Portions of the lighting fixture are shown broken away in FIGS. 1 and 2 for illustrative purposes only.