Auto merge of #69854 - pietroalbini:stable-next, r=Centril

[stable] Release 1.42.0

This PR prepares the release artifacts of Rust 1.42.0, and cherry-picks the following PRs:

* https://github.com/rust-lang/rust/pull/69754: Update deprecation version to 1.42 for Error::description
* https://github.com/rust-lang/rust/pull/69753: Do not ICE when matching an uninhabited enum's field
* https://github.com/rust-lang/rust/pull/69522 / https://github.com/rust-lang/rust/pull/69853: error_derive_forbidden_on_non_adt: be more graceful
* https://github.com/rust-lang/rust/pull/68598:  Fix null synthetic_implementors error

In addition, the release notes are updated to include the remaining compatibility notes.

r? @Centril