The ornamental design for a boot, as shown and described.
FIG. 1 is a bottom perspective view of a boot in accordance with the new design;
FIG. 2 is a bottom view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a front view thereof; and,
FIG. 7 is a rear view thereof.
The boot upper shown in broken lines in FIGS. 1-7 is for environmental purposes only and forms no part of the claimed design. The broken lines shown in each arch area of FIGS. 1 and 2 represent boundaries of the design with the lines themselves and the areas within them forming no part of the claimed design.