v0.8.0-alpha.19

What's Changed

• Roll pinned nightly and stable toolchains by @joshlf in #1612
• [ci] Roll pinned Kani version by @google-pr-creation-bot in #1611
• [pointer] Update requirements for zero-sized types by @joshlf in #1614
• Write some safety proofs by @joshlf in #1615
• Redocument derive(IntoBytes) to reflect current implementation by @jswrenn in #1616
• Tighten soundness of addr_of! uses by @joshlf in #1617
• [Ref] Make methods into associated functions by @joshlf in #1618
• FromZeros boxed slice method supports slice DSTs by @joshlf in #1478
• Implement TryFromBytes for unsized UnsafeCell by @joshlf in #1619
• Add safety comment for MaybeUninit UnsafeCell by @joshlf in #1620
• Release 0.8.0-alpha.19 by @google-pr-creation-bot in #1621

Full Changelog: v0.8.0-alpha.18...v0.8.0-alpha.19