The ornamental design for a hat, as shown and described.
FIG. 1 is a perspective view of a hat, showing my new design;
FIG. 2 is a right view of FIG. 1, the left view being a mirror image thereof;
FIG. 3 is a top plan view of FIG. 1;
FIG. 4 is a bottom plan view of FIG. 1;
FIG. 5 is a front view of FIG. 1; and,
FIG. 6 is a rear view of FIG. 1.
The evenly spaced broken lines depict portions of the hat that form no part of the claimed design. The dot-dash-dot broken lines define the bounds of the claim and form no part of the claimed design.