Remove debug bound on pin generics

[robamu]

The previous auto-implementation automatically added Debug bounds on all pin instances. However, not every HAL might have a debug implementation on the pin structures.

I think it would be better for this library if the pins do not have that bound. It makes the library easier to use, because each time those bounds are violated, I have to fork a HAL and add the debug bound manually (which can be non-trivial, e.g. in the case of the Raspberry Pi Pico HAL). I am a big fan of adding the Debug bound on every public structure in my libraries, but I think in this case the advantages of losing a little bit of information (not that much, the user can still see whether it is a 4 or 8 pin bus) and increase the flexibility of the library are worth it.