The ornamental design for a utilitybag, as shown and described.
FIG. 1 is a front view of a utility bag showing my new design;
FIG. 2 is a rear view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a bottom view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a perspective front view thereof.
The broken lines illustrate portions of the utility bag and form no part of the claimed design. The strap is shown with a symbolic break in its length. The appearance of any portion of the article between the break lines forms no part of the claimed design.