Tronxy sensor mount

I remixed the sesor mount of the E3D V6 carrier mount by johho (https://www.thingiverse.com/thing:2243525).

- I put some holes in it to mount the sensor with screws instead of glue or double sided tape.
- I made it a little bit smaller (0.2 mm), the original did not fit well into the carrier
- I made the nut hole a little bit wider, so I can fit a M3 nut into it.