update embedded-hal-async to latest version

[arlyon]

A new release would also drop heapless 0.7 which means I can update some lagging versions in esp-wifi (and drop all my local patches :) )

esp-rs/esp-wifi-sys#408

I didn't update to rc 3 since there are some breaking changes that still need to propagate through the ecosystem (in my case, esp32-hal and friends)

See here https://github.com/rust-embedded/embedded-hal/blob/master/embedded-hal/CHANGELOG.md#v100-rc3---2023-12-14

[ivmarkov]

Not sure why the CI did not trigger on your PR, but simply raising embedded-hal-async to RC2 won't work.

See here what needs to be changed.

Anyway - since rust-stable is already in the works, perhaps we can close your PR, and I'll open another one for the rust-stable branch?

[ivmarkov]

Closing because #67 is merged now.