The ornamental design for a “boot insert,” as shown and described.
FIG. 1 is a perspective view of the bottom and front of the boot insert;
FIG. 2 is a right side plan view of the boot insert;
FIG. 3 is a front plan view of the boot insert;
FIG. 4 is a rear plan view of the boot insert;
FIG. 5 is a view looking upwardly at the boot insert from below;
FIG. 6 is a view looking downwardly at the boot insert from above; and,
FIG. 7 is a perspective view of the boot insert in use.
The left side view of the boot insert is identical to the right side view depicted in FIG. 2. The broken-lines of FIG. 1 depict a decorative pattern on the inside of the boot insert. The broken-lines of FIGS. 1 and 4 depict a seam. The broken-lines of FIG. 6 depict a boot and the decorative pattern of FIG. 1 now folded about the cuff of the boot. These broken line features are depicted for illustrative purposes only, and form no part of the claimed design.