The ornamental design for a shower tray, as shown and described.
FIG. 1 is a top, front, right perspective view of a shower tray showing my new design;
FIG. 2 is a top view thereof;
FIG. 3 is a front view thereof, the rear view being a mirror image thereof;
FIG. 4 is a right side view thereof, the left side view being a mirror image thereof; and,
FIG. 5 is an enlarged view of the region identified by the number “5” in FIG. 2 thereof.
The even-length broken lines showing the remainder of the shower tray are for environmental purposes only and form no part of the claimed design. In FIG. 2, the uneven-length broken lines identified by the number “5” adjacent to the shaded area do not form part of the claimed design and only serve to illustrate the region drawn enlarged in FIG. 5.