The ornamental design for deck slat, as shown and described.
The FIGURE is a perspective view of a deck slat showing our new design.
The broken lines shown in the drawings are for illustrative purposes only and form no part of the claimed design. Additional views have not been provided as the ornamental features are fully disclosed in perspective. The illustrated embodiments of the design are not limited to the exact details shown in the drawings, since equivalents and colorable imitations thereof will be evident to a person of ordinary skill in the art. Thus, within the scope of the appended claim, which is intended to cover only the ornamental and novel elements shown in the drawings, the invention may be practiced otherwise than as specifically shown and described herein.