The ornamental design for a boot with a notch, as shown and described.
FIG. 1 is a left side view of a boot with a notch, showing my new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a perspective view thereof; and,
FIG. 4 is a front view thereof.
The evenly spaced dotted lines represent unclaimed stitching. The dash dot dot dash lines immediately adjacent the solid-line portions of the design form the boundary of the design, and forms no part of the claimed design.