The ornamental design for a buffet, as shown and described.
FIG. 1 is a perspective view of the buffet of my new design from the front
and one end;
FIG. 2 is a top plan view of the buffet;
FIG. 3 is a front elevation view of the buffet, and
FIG. 4 is a right end elevation view of the buffet. A right end view of the
buffet would be virtually the same. The back and bottom of the buffet are
plain and unornamented.