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 lateral side view thereof;
FIG. 3 is a medial side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof; and,
FIG. 6 is a top view thereof.
The broken line showing of the eyelets, the bottom edge and the remainder of the shoe is for illustrative purposes only and forms no part of the claimed design.