I claim the ornamental design for a swing, substantially shown and described herein.
FIG. 1 is a front-right perspective view of the swing according to the new design;
FIG. 2 is a left side view view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines showing structural elements in the drawings are included for the purpose of illustrating non-claimed subject matter, and form no part of the claimed design.