The ornamental design for a shoe upper, as shown and described.
FIG. 1 is a front perspective view of a shoe upper showing my new design;
FIG. 2 is a side view thereof; and,
FIG. 3 is a rear perspective view thereof.
The broken line immediately adjacent to the rear bottom portion of the shaded area represents an unclaimed boundary of the design. The broken lines showing the remainder of the shoe are for environmental purposes only and form no part of the claimed design.