Magnetic B-Drive Motor Cable Cover for Voron 2.4

I added a gantry servo for for the Filametrix filament cutter.  This left an exposed wire running along the top of the B-drive unit.

Since the B-drive unit doesn't have the extra screw holes for a cable cover (like the A-unit does), I made this magentic.  Two 6x3 magnets will snap in place over two of the screws.

The servo mount is not my design.  For those interested, you can find it here: https://www.thingiverse.com/thing:6584232