bump embedded HAL dependencies and update async API

[robamu]

I tested both the blocking API and the updated asynchronous non-blocking API on a Raspberry Pi Pico.

One small thing where I wasn't sure what the best solution is:

dht11::asynch::read vs. dht11::read_async and the same for dht22 of course.

[michaelbeaumont]

One small thing where I wasn't sure what the best solution is:

Maybe there's some precedent here on maintaining async and non-async interfaces?

[robamu]

They are separated already, it's just a style question I guess. I would actually prefer the dht11::read and dht11::read_async version at this point. Or do you mean something else?