The ornamental design for a hat, as shown and described.
FIG. 1 is a top front perspective view of a hat;
FIG. 2 is a right side elevation view thereof, the left side elevation view being a mirror image thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The broken lines shown along and just inward of the opening of the hat in FIG. 6 defines the bounds of the claimed design and forms no part of the claim. The remaining broken lines shown in the drawings depict portions of the hat that form no part of the claimed design.