The ornamental design for a bucket, as shown and described.
FIG. 1 is a top, front, right perspective view of a bucket showing my new design;
FIG. 2 is a top, left perspective view thereof;
FIG. 3 is a right side view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a front view thereof; and,
FIG. 7 is a top view thereof.
The broken lines immediately adjacent to the shaded area represent unclaimed boundaries of the design. The broken lines showing the remainder of the bucket are for environmental purposes only and form no part of the claimed design.