The ornamental design for switch, as shown and described.
FIG. 1 is a front view of a switch, showing our new design;
FIG. 2 is a back view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a front right perspective view thereof; and,
FIG. 8 is a back left perspective view thereof.
The broken line showing of the interior of the switch in FIGS. 3, 4, 5, and 6 is included for the purpose of illustrating unclaimed detail and forms no part of the claimed design.