The ornamental design for a universal serialbushub, as shown and described.
FIG. 1 is a perspective view of a universal serial bus hub showing my design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is an elevational view facing part B thereof;
FIG. 5 is an elevational view facing part C thereof; and,
FIG. 6 is an elevational view facing part A thereof.
The broken lines are for illustrative purposes only and form no part of the claimed design. Elevational views facing parts D and E are mirror images of FIGS. 4 and 5, respectively, and therefore omitted.