The ornamental design for a utilityknife, as shown and described.
FIG. 1 is a perspective view of an embodiment of a utility knife of our design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view therefor;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a right-side view thereof; and,
FIG. 7 is a left-side view thereof.
The broken lines depict portions of the utility knife in which the design is embodied that are not considered part of the claimed design. The broken line showing of the blade is provided for purposes of environment and forms no part of the claimed design.