Next release planning

[jqnatividad]

Especially with the itoa reaching v1 and dtoa 0.4.8 replaced by ryu v1.

#588

[djc]

I think this will need to be 0.22, since #576 changed the available features. I have not yet audited the rest of the PRs to see if there are API-incompatible changes, but I wouldn't be surprised if there were more.

[djc]

Submitted #647 to deal with the pinned dependency for async-std.

[RalfJung]

It'd be good to get a semver-compatible update that depends on itoa 1.0. This crate is one of the most popular crates that still depends on itoa 0.4, which uses the deprecated mem::uninitialized function. On recent nightly builds of the compiler, that function has become a lot slower in order to mitigate the many ways in which it is used incorrectly throughout the ecosystem. We'd like to move even further and add future-compatibility warnings against mem::uninitialized, which would show up everywhere that itoa is in the dependency tree.

[djc]

#666 prepares a 0.21.6 release.

[djc]

0.21.6 has been released, thanks!