Later rust versions produce a non-working firmware binary

I noticed this yesterday (2023-06-14) - I built and flashed firmware from `rustc 1.70` and the firmware failed to start up and enumerate as a USB device.

I haven't investigated the exact cause yet, or where it's crashing.

I also haven't identified the exact point in rustc versioning where it fails to work, but I can confirm that `rustc 1.60` does not exhibit this behavior.