[proposal] release 0.3.0

[ryankurte]

Swaps digital trait default to digital::v2 (breaking change), as the next step in the planned digital::v1 deprecation, as an alternative to rust-embedded/wg#393.

This approach is aligned with all other HAL traits (where Infallible is returned for infallible implementations), minimises complexity (by not introducing multiple options that must be effectively communicated to all users, or the opportunity for incompatibility due to use of the incorrect trait) with the end goal of removing the version numbers and having a single set of fallible digital::* traits.

I had hoped to port the compatibility shims back to the v0.2 series, however, this seems impossible to do without cyclic dependencies.

Dependencies

• embedded-hal release 0.2.4 Release 0.2.4 semver-trick for embedded-hal v0.3.x release #174 containing the semver-trick to maintain backwards compatibility

Impact

• HAL consumers using digital::* traits directly will need to update to fallible types
• HAL consumers using digital::v1::* or digital::v2::* will observe no change

Next steps

• HAL v0.4.x series should remove digital::{v1, v1_compat, v2_compat} to complete the migration

[rust-highfive]

r? @ithinuel

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[ryankurte]

Closing as replaced by #192