I claim the ornamental design for a corset, as shown and described.
FIG. 1 is a front side view of a corset, showing the new design;
FIG. 2 is a rear view thereof;
FIG. 3 is a right view thereof;
FIG. 4 is a front right perspective view of the corset, shown in an alternate configuration in a state of use on a person's body, with the front left perspective view being a mirror image thereof;
FIG. 5 is a front view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a left view thereof.
The broken lines in FIGS. 4-6 showing a person depict environmental structure that forms no part of the claimed design. The broken lines on the corset itself depict stitching that forms part of the claimed design. The person's body is shown with symbolic breaks in its length. The appearance of any portion of the article between or beyond the break lines forms no part of the claimed design.