The ornamental design for a packagingbox, as shown and described.
FIG. 1 is a front perspective view of a packaging box, showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof;
FIG. 7 is a bottom plan view thereof; and,
FIG. 8 is a front perspective view thereof in an alternate position.
The broken lines showing of a body of the packaging box in all views are for the purpose of illustrating a portion of the article in which the design is embodied and form no part of the claimed design.