chore: Remove async-trait

[kayabaNerve]

Description

Removes async-trait for usage of RPIT.

Notes & open questions

libp2p's MSRV has included RPIT for a while now, making this possible. The Send bounds follow the behavior from async-trait. async-trait's generation of Pin<Box<dyn Future>> also provided Unpin which has not been a preserved bound EXCEPT in the test code which required it in in-tree call sites. Moving forward, callers expecting Unpin should wrap their futures themselves with Box::pin.

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[kayabaNerve]

libp2p-request-response already has an unpublished breaking change release in-tree. Most of the modified crates solely had their libp2p-request-response integrations edited, and already had a CHANGELOG entry for their update to the latest version.

libp2p-dns is weird. It has a hidden, public API item I did make breaking changes to and did not already have an unpublished breaking change in release (solely a patch release). It doesn't need a breaking change release if the hidden API entry is considered NOT part of the public API. I assumed that yes, there would be issues to change it without a new release however (as it has no in-tree users so it presumably services out-of-tree crates), and did bump the minor version. If these changes are an area of contest, they can be moved to a distinct PR as the libp2p-request-response changes are my priority.

No documentation/tests were needed for this, hence the unchecked boxes in the checklist.

It'd be great to have this included prior to the new releases which are about to occur. Sorry if it's too last minute.

[elenaf9]

Hi @kayabaNerve, thank you for the PR!

Could you share a bit about the motivation for removing the use of async-trait?

It'd be great to have this included prior to the new releases which are about to occur. Sorry if it's too last minute.

We are planning to release today, so unfortunately it's a bit too short notice. If it's very urgent we could cut another release soon-ish, but it be great to know why.

[kayabaNerve]

It's an unnecessary dependency with worse codegen? It only existed because RPIT wasn't stable and RPIT has been stable for months now. libp2p's MSRV includes RPIT as well, so there really is no blocker.