The ornamental design for a golf accessory, as shown and described.
FIG. 1 is a perspective view of the golf accessory with the broken lines showing a golf ball, two golf tees, a divot repair tool and a ball marker being for the purposes of illustrating environment and form no part of the claimed design.
FIG. 2 is a front side elevational view thereof;
FIG. 3 is a left side elevational view thereof, the right side being a mirror image thereof;