The ornamental design for a bolt, as shown and described.
FIG. 1 shows a top view of a bolt made in accordance with the design of the present invention;
FIG. 2 shows a side view of the bolt of FIG. 1 made in accordance with the present invention, each of the other side views being the same but omitting the hole;
FIG. 3 shows a perspective view of the bolt of FIG. 1 made in accordance with the design of the present invention; and,
FIG. 4 shows a bottom view of the bolt of FIG. 1.
The broken lines shown on the drawings are for illustrative purposes only and form no part of the claimed design.