Release 0.24.0

[Mingun]

Since asynchronous support is just around the corner, it's time to start a release process. It is unlikely in the nearest future we will manage to add still something important, and would be impolite to keep people waiting until we make everything that we intended.

So I'll plan to release 0.24.0 as soon as async support will merged. If someone thinks that a certain issue surely has to be included, then let know in comments.

Checklist:

• [x] Fix #435
• [ ] Merge #450
• [ ] cargo fmt --check pass
• [ ] cargo test pass
• [ ] cargo test --all-features pass
• [ ] cargo test --all-features --benches pass
• [ ] cargo test --features serialize pass
• [ ] cargo test --features encoding pass
• [ ] cargo doc --all-features --document-private-items without warnings
• [ ] RUSTDOCFLAGS="--cfg docs_rs" cargo +nightly doc --all-features and check generated documentation for missing / unclear things
• [ ] cargo package for final check
• [ ] Update version in Cargo.toml
• [ ] Update Changelog.md with date of release, add new empty Unreleased headings
• [ ] Check that we are unaffected by https://github.com/rust-lang/cargo/issues/10954
• [ ] cargo publish
• [ ] Create and push tag 0.24.0
• [ ] Create a Release on GitHub (If @dralley writes a few words, I fear for my grammar :innocent:)

[dralley]

Not sure that the checklist needs to include things that are already checked by the CI?

[CrayfishGo]

Has this version been released yet？

[Mingun]

Not yet. I'll plan to do a release on next weekend, before the end of August.

[Mingun]

Wooh! Released 0.24.0