The ornamental design for a headwear, as shown and described.
FIG. 1 is a perspective view of a headwear, showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left-side elevational view thereof;
FIG. 5 is a right-side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The dash-dot broken lines depict details of the headwear that form no part of the claimed design. The dashed broken lines depict stitching that forms part of the claimed design.