The ornamental design for a stringlight, as shown and described.
FIG. 1 is a perspective view of a string light showing my new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a left side elevational view thereof; and,
FIG. 8 is a right side elevational view thereof.
The broken lines in the drawings depict the bounds of the claimed design. The string light is shown with a symbolic break in its length. The appearance of any portion of the string light between the break lines and the boundary lines form no part of the claimed design.