Expose async-broadcast in smol

[notgull]

@zeenix and I have been discussing if it would be possible to expose async-broadcast in smol, under a "broadcast" module. I'm a fan of this.

The following would need to happen first:

• async-broadcast needs to be released as version 1.0
• async-broadcast needs to explicitly follow smol's MSRV policy.

cc @smol-rs/admins

[zeenix]

The following would need to happen first:

• async-broadcast needs to be released as version 1.0
• async-broadcast needs to explicitly follow smol's MSRV policy.

Sure, makes sense. I'll look into both of these.

Do you think we also need to resolve smol-rs/async-broadcast#58 ? Fortunately there is a PR for it already and it just needs some adjustments I think. Unfortunately the author seems to have disappeared.