The ornamental design for a shower pan, as shown and described.
FIG. 1 is a top plan view showing a first embodiment of the new design. The bottom of the article is flat and devoid of surface ornamentation, and is therefore not shown.
FIG. 2 is a top left perspective view thereof; and,
FIG. 3 is an enlarged fragmentary view of a portion of the design. The double object lines surrounding the drain grate and defining the opening in the floor shown in the enlargement of FIG. 3 do not appear in FIGS. 1 and 2.
The front, back, left and right side elevational views of the article are flat and devoid of surface ornamentation, and are therefore not shown.