The ornamental design for a lightingfixture, as shown and described.
FIG. 1 is a bottom, front, right perspective view of a lighting fixture showing our new design;
FIG. 2 is a bottom view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a front view thereof;
FIG. 7 is a rear view thereof; and,
FIG. 8 is a bottom, front perspective view thereof.
The broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The broken lines showing the remainder of the lighting fixture form no part of the claimed design.