The ornamental design for a headgarment, as shown and described.
FIG. 1 is a front view of a head garment, as worn by a person.
FIG. 2 is a back view of the head garment of FIG. 1, as worn by a person.
FIG. 3 is a left-side view of the head garment of FIG. 1, as worn by a person.
FIG. 4 is a right-side view of the head garment of FIG. 1, as worn by a person; and,
FIG. 5 is a top-down view of the head garment of FIG. 1, as worn by a person.
The broken lines illustrate portions of the person's head and body to provide context for the head garment and form no part of the claimed design. The broken lines within the bounds of the head garment depict stitching which is part of the claimed design.