We claim the ornamental design for a boot, as shown and described.
FIG. 1 is a perspective view of a boot showing the new design;
FIG. 2 is a left side elevation view thereof;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a rear elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines adjacent to the shaded areas depict boundaries of the claim and form no part of the claimed design. All other broken lines are directed to unclaimed portions of the boot and form no part of the claimed design.