Publish `0.5` release

[kpark-hrp]

It has been a while, since the last tower release...

I would like to leverage the &mut references in Retry and batteries included ExponentialBackoff. 😃

[davidpdrsn]

I believe master has breaking changes so it's probably worth seeing if there are other things to fix before doing a new major.

Tower is unfortunately a little understaffed currently I believe. I'm personally busy with axum and tower-http.

[olix0r]

There's an 0.5 milestone that includes some remaining items. I agree that tower needs some attention/maintenance. We're also a bit saturated with Linkerd work but we may have some more time to help in ~April.

[LucioFranco]

I think we can put together a final 0.5 release. I am actively (started as of 2 days ago xD) working on tower 1.0 and its future direction. Mainly focused on the service trait for now.

[cuviper]

FWIW, #741 has a breaking change that could be included in a bump.

[jplatte]

Same for #750, except it's a (small) proposal in an issue, without an implementation.

[djc]

Given the lack of resources to drive this forward in a big way, maybe we can get a 0.5 out with a bunch of dependency updates? I would be willing to help out with that if necessary.

[jplatte]

This has happened! I don't have the permissions to close it though 😅