The ornamental design for a shelvingunit, as shown and described.
FIG. 1 is a top perspective view of a shelving unit;
FIG. 2 is a front view of the shelving unit.
FIG. 3 is a back view of the shelving unit.
FIG. 4 is a first side view of the shelving unit.
FIG. 5 is a second side view, opposite of the first side view, of the shelving unit.
FIG. 6 is a top view of the shelving unit.
FIG. 7 is a bottom view of the shelving unit; and,
FIG. 8 is a bottom perspective view of the shelving unit.
The dotted line illustrations of under-shelf storage modules on casters are for illustrative purposes of the environment of the shelving unit and form no part of the claimed design.