The ornamental design for a raincoat, as shown and described.
FIG. 1 is a front elevational view of a raincoat showing my new design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a front perspective view thereof.
The broken lines in the drawings showing of the stitching are for the purpose of depicting portions of the raincoat that form no part of the claimed design.