I claim the ornamental design for a utility knife, as shown and described.
FIG. 1 is a front, left side perspective view of the utility knife.
FIG. 2 is a rear, right side perspective view
FIG. 3 is a top view thereof.
FIG. 4 is a bottom view thereof.
FIG. 5 is a right side view thereof.
FIG. 6 is a left side view thereof.
FIG. 7 is a front view thereof; and,
FIG. 8 is a rear view thereof.
The broken lines in the drawings are for the purpose of illustrating unclaimed portions of the utility knife and form no part of the claimed design.
The shading lines shown in the drawings represent the approximate three-dimensional contour of the design, and are not intended to indicate surface decoration.