The ornamental design for a shoe upper, as shown and described.
FIG. 1 is a rear perspective view of a shoe upper showing my new design;
FIG. 2 is a rear view thereof; and,
FIG. 3 is a second rear perspective view thereof.
The broken lines immediately adjacent to the photographic 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.