New release for embedded-hal digital async traits

[jerrysxie]

Hi, I implemented embedded-hal digital async traits for an IO expander driver here: OpenDevicePartnership/pcal6416a#21, and I would like to publish a new version of the IO expander driver crate.

However, I learned that the embedded-hal digital async traits for OutputPin, StatefulOutputPin and InputPin are unreleased. Is there any upcoming plan to do a new release anytime soon? Thanks.