The ornamental design for a knithat, as shown and described.
FIG. 1 is a front elevational view of a knit hat showing my new design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The dash-dash broken lines along the knit hat depict features of the knit hat that form no part of the claimed design. The dash-dot-dash broken lines and the unshaded areas adjacent to the dash-dot-dash broken lines define portions of the knit hat that form no part of the claimed design.