Round luminaire

The design is the visual features of the entirety of the Round Luminaire shown in the drawings, whether those features are features of one of shape, configuration, ornament, or pattern, or are a combination of any of these features.Drawings of the design are included.FIG. 1 is a bottom perspective view of a round luminaire, illustrating the design;FIG. 2 is a bottom view thereof;FIG. 3 is a side view thereof;FIG. 4 is a top view thereof;FIG. 5 is a top perspective view thereof;FIG. 6 is a bottom perspective view of a round luminaire, illustrating a first variant of the design;FIG. 7 is a bottom view thereof;FIG. 8 is a side view thereof;FIG. 9 is a front/back view thereof;FIG. 10 is a bottom perspective view of a round luminaire, illustrating a second variant of the design;FIG. 11 is a bottom view thereof;FIG. 12 is a side view thereof; andFIG. 13 is a front/back view thereof.