The ornamental design for a tray, as shown and described.
FIG. 1 is a top perspective view of an embodiment of a tray.
FIG. 2 is a side view of the tray of FIG. 1.
FIG. 3 is a side view of the tray of FIG. 1; and,
FIG. 4 is a top plan view of the tray of FIG. 1.
The evenly-spaced broken lines show portions of the tray that form no part of the claimed design. None of the broken lines form part of the claimed design. In addition, the dash-dot-dash broken lines in FIGS. 2 and 3 depict boundaries, and the areas within form no part of the claimed design.