Prusa i3 MK3S fs-cover with bigger slot for shimmed IR sensor

When spacers are used to shim the IR filament sensor, original fs-cover no longer fits. I fixed this by making the slot bigger.

I printed mine on the MK3S from Filament PM PLA+ with 0.20mm SPEED profile in PrusaSlicer, but since the original part is PETG, that would also be a good choice. 15% infill, no supports.

Slot at the bottom of fs-cover now reaches further to the back to accommodate raised IR sensor PCB (I had to shim my IR filament sensor 0.7 mm with https://www.printables.com/model/25728-prusa-mk3s-ir-sensor-spacer-set to get it to return from “1” to “0” reliably).