The ornamental design for a boot, as shown and described.
FIG. 1 is front left perspective view of a boot showing my new design;
FIG. 2 is front view of the design shown in FIG. 1;
FIG. 3 is a rear view of the design shown in FIG. 1;
FIG. 4 is a right side view of the design shown in FIG. 1;
FIG. 5 is a left side view of the design shown in FIG. 1;
FIG. 6 is a top view of the design shown in FIG. 1; and,
FIG. 7 is a bottom view of the design shown in FIG. 1.
The even-spaced dashed broken lines in the figures illustrate environmental structure that forms no part of the claimed design. The dash-dot-dash broken lines depict the bounds of the claim. The area within the dash-dot-dash lines and up to the boundary line created by the photographic portion form the claimed design.