Embassy stm32 blinky test

Based on embassy examples, this project provides a minimal configuration for blinking a stm32 blue pill, thanks to embassy runtime and hardware abstraction layer.

For flashing the firmware, you need an stm32 blue pill connected to a stlink v2 single wire debug probe;

then you only need to run the command:

cargo run --release

You will see GPIO B2 and B11 blinking in the opposite direction.