FIG. 1 is a perspective view of a first embodiment of the luminaire showing the new design; FIG. 2 is a front elevational view thereof; FIG. 3 is a bottom view thereof; FIG. 4 is a top plan view thereof; FIG. 5 is a perspective view of a second embodiment of the luminaire of the new design; FIG. 6 is a front elevational view thereof; FIG. 7 is a bottom view thereof; and, FIG. 8 is a top plan view thereof. The broken line environmental showing is for illustrative purposes only and forms no part of the claimed design.