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, wherein the bottom, rear left perspective view is identical thereto; and,
FIG. 2 is a top, front, right perspective view thereof, wherein the top, rear left perspective view is identical thereto.
The uneven-length broken lines represent unclaimed boundaries of the claimed design. The even-length broken lines showing the remainder of the lighting fixture are for illustrative purposes only and form no part of the claimed design. The middle portion of the lighting fixture is broken away in FIGS. 1 and 2 to indicate no particular length.