The ornamental design for a boot, as shown and described.
FIG. 1 is a perspective view of the boot showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof shown with a portion of the boot shown in an alternate position; and,
FIG. 7 is a right side view thereof with a top portion of the boot removed from the bottom portion of the boot.
The broken line is for illustrative purposes only and forms no part of the claimed design. The surface shading illustrated in the drawings is provided merely to highlight the contour of the design; it is not intended to be illustrative of texture or gloss.