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 lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The broken lines showing the remainder of the shoe represent unclaimed subject matter and form no part of the claimed design.