The ornamental design for a swing, as shown and described.
FIG. 1 is a front view of the swing.
FIG. 2 is a left side view of the swing.
FIG. 3 is a right side view of the swing.
FIG. 4 is a left side, cross-sectional view of the swing, taken along line 4-4 of FIG. 5.
FIG. 5 is a top view of the swing.
FIG. 6 is a bottom view of the swing.
FIG. 7 is a front perspective view of the swing; and,
FIG. 8 is a front perspective view of the swing supporting a user.
The inclusion of the supporting structures in the foregoing figures is for illustrative purposes only and forms no part of the claimed design. In addition the broken line disclosure is for illustrative purposes only and forms no part of the claimed design.