The ornamental design for a shelving supportbracket, as shown and described.
FIG. 1 is a enlarged, three-dimensional view of my new design from the front and Left side of the shelving support bracket in accordance with the present invention. The circles on the surface of the shelving support bracket indicating holes.
FIG. 2 is a front view of the shelving support bracket, shown with three boards properly aligned, the boards being shown in broken lines and forming no part of the claimed design.