The ornamental design of an overshoe, as shown in the figures and described.
FIG. 1 is a top perspective view of an overshoe;
FIG. 2 is a top plan view of the overshoe of FIG. 1;
FIG. 3 is a bottom plan view of the overshoe of FIG. 1;
FIG. 4 is a front elevation view of the overshoe of FIG. 1;
FIG. 5 is a rear elevation view of the overshoe of FIG. 1;
FIG. 6 is a right side elevation view of the overshoe of FIG. 1; and,
FIG. 7 is a left side elevation view of the overshoe of FIG. 1.
In the figures, shading represents contour and not any particular color. Structure that is not part of the claimed design is represented in the figures by broken lines.