Updated SRAM 12t X-Sync pulley for 1x drivetrains

This is an updated version of the "SRAM 12t X-Sync pulley for 1x drivetrains" by Chris Heerschap. I made the fit for the bearing a little bit tighter and added two rings on the outsides to hold the bearing in place (just like the original Sram wheels).

There is also a litte bit more clearance to the derailleur cage, because on my Sram GX the wheel was rubbing against the cage.