🎁 prepare release 0.5.0

[JakeChampion]

Cutting a new release, this currently contains steps 1 through to 5 of Releasing Viceroy.

1. Make sure the Viceroy version has been bumped up to the current release
   version. You might need to bump the minor version (e.g. 0.2.0 to 0.3.0) if
   there are any semver breaking changes. Review the changes since the last
   release just to be sure.
2. Update the Cargo.lock files by running make generate-lockfile.
3. Update CHANGELOG.md so that it contains all of the updates since the
   previous version as its own commit.
4. Create a local branch in the form release-x.y.z where x, y, and z are
   the major, minor, and patch versions of Viceroy and have the tip of the
   branch contain the Changelog commit.
5. Run make ci locally to make sure that everything will pass before pushing
   the branch and opening up a PR.

[acfoltzer]

Gah, I just noticed that there's a semver break with the new HandleError::InvalidPendingKvLookupHandle variant. We need to mark that #[non_exhaustive] if it's gonna be publicly exposed (this probably applies to some other types as well).

For now, would you mind changing the crate versions to 0.5.0 before we release?

[acfoltzer]

Oh, the changes to insert_pending_request are also part of the public interface to viceroy-lib, which causes breakage as well. I think we're probably exposing more than we need to from this crate and laying semver traps for ourselves. I'll make a follow-up issue for us to examine that and hopefully cut a 0.6.0 that makes future changes less disruptive.

[acfoltzer]

Thank you! Approved to advance to step 6 🚀

[acfoltzer]

Sorry for delay on this, thanks for closing the loop ➰