The ornamental design for a wreath, as shown and described.
FIG. 1 is a perspective view of a wreath showing my new design;
FIG. 2 is a front elevational view with the rear view being identical thereof; and,
FIG. 3 is a right side elevational view with the left side, top and bottom views being identical thereof.
The broken line showing of FIGS. 1 and 2 of the illumination created by the lights is included for the purpose of illustrating only and forms no part of the claimed design.