Electronics Tray for The 100

Updated the electronics tray to provide a bit more room between the PSU and screw terminals on the SKR Pico. If the PSU mounts using the stock holes then this isn't necessary - however, my PSU required an adapter (https://www.printables.com/model/600391-psu-mount-for-the-100, also my design) which pushed it out just enough to make connecting the heater and power wires too tight for comfort.