The ornamental design for a sling latch, as shown and described.
FIG. 1 is a perspective view of a sling latch showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a left side elevational view thereof; and,
FIG. 7 is a right side elevational view thereof.
The broken lines immediately adjacent the shaded areas represent the bounds of he claimed design while all other broken lines are directed to environment and are for illustrative purpose only; and form no part of the claimed design.