The ornamental design for a toolbox, as shown and described.
FIG. 1 is a front elevational view of a toolbox showing my new design; FIG.
2 is a rear elevational view thereof; FIG. 3 is a left/right side
elevational view thereof; FIG. 4 is a top plan view thereof; FIG. 5 is a
down plan view thereof; and, FIG. 6 is a perspective view thereof.