I claim, the ornamental design for a luminaire, as shown and described.
FIG. 1 illustrates a top perspective view of a luminaire, showing new and ornamental design;
FIG. 2 illustrates a side elevation view thereof;
FIG. 3 illustrates a front elevation view thereof;
FIG. 4 illustrates a top plan view thereof;
FIG. 5 illustrates a bottom plan view thereof; and,
FIG. 6 illustrates a bottom perspective view thereof.
The opposite side elevation view is a mirror image of the shown side elevation view, and the rear elevation view is a mirror image or the front elevation view.