The ornamental design for seat, as shown and described.
FIG. 1 is a perspective view of a first embodiment of a seat showing my new design. The broken lines, showing legs, are included for the purpose of illustrating environment and form no part of the claimed design;
FIG. 2 is a front elevational view;
FIG. 3 is a right side elevational view. The left side is identical;
FIG. 4 is a rear elevational view;
FIG. 5 is a top plan view;
FIG. 6 is a bottom plan view; and,
FIG. 7 is an alternate perspective view of a second embodiment similar to FIG. 1.