Related to the USB chat, but for non-OTG. To upgrade `usb-device` and `usbd-serial`, there are breaking changes required. Does anyone know how to do this?

```toml
usb-device = "^0.3.1"
usbd-serial = "^0.2.0"
```

I think it's looking for a new `UsbBus` trait, or something to that effect