I claim the ornamental designs for a lighting fixture, as shown and described.
FIG. 1 is a front perspective view of a lighting fixture. This fixture has mirror image symmetry (one hundred eighty degree overall rotational symmetry, and mirror image symmetry along a first vertical imaginary plane and also mirror image symmetry along a second vertical imaginary plane, with the first and second vertical imaginary planes being orthogonal to each other). The candles, glasses, and support stems each have a circular horizontal cross-section; and,
FIG. 2 is a top view of the lighting fixture of FIG. 1.
The broken lines shown in the drawing represent portions of the light fixture that form no part of the claimed design.