I claim the ornamental design for a sports boot, as shown and described.
FIG. 1 is a perspective view of a sports boot, seen from the right side and front of the boot, showing my new design;
FIG. 2 is another perspective view thereof, seen from the left side and rear of the snowboard boot;
FIG. 3 is a right side view thereof; and,
FIG. 4 is a left side view thereof.
The broken lines showing portions of a liner, tongue, and sole of the boot, are for illustrative purposes only and form no part of the claimed design. The broken lines showing the region of the heel, the front of the lower leg portion, and the top of the forefoot portion of the boot, define the bounds of the claim.