v2.0.0

[notgull]

• Breaking: Seal extension traits. (#20)
• Breaking: Remove unsafe implementations of the FromRawFd/FromRawHandle traits. (#26)
• Avoid using a build.rs script for feature autodetection. (#17)
• Remove the autocfg dependency. (#18)
• Avoid a heap allocation in the ReadDir implementation. (#23)

[notgull]

We may want to include https://github.com/smol-rs/async-fs/pull/26 as well

[notgull]

I'll wait to merge this until we're ready to merge all of the breaking change PRs. That way we can update all at once.