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;
FIG. 3 is a second 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.