The ornamental design for a gateway, as shown and described.
FIG. 1 is a perspective view of a gateway showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a side view thereof;
FIG. 5 is another side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is an enlarged view of the circled portion thereof in FIG. 2.
The evenly spaced broken lines that are immediately adjacent to the claim, and define unshaded regions, represent the bounds of the claim, while all other evenly spaced broken lines are directed to environment and the dot-dot-dash broken lines in FIGS. 2 and 8 are for the purpose of illustrating a partially enlarged view; the broken lines form no part of the claimed design.