The 1.57.0 pre-release is ready for testing. The release is scheduled for this Thursday, December 2nd. Release notes can be found here.
You can try it out locally by running:
RUSTUP_DIST_SERVER=https://dev-static.rust-lang.org rustup update stable
The index is https://dev-static.rust-lang.org/dist/2021-11-30/index.html. You can leave feedback on this thread.
I also wanted to followup on a suggestion for change in recommended testing strategy; pre-release testing strategy · Issue #16 · rust-lang/release-team · GitHub is now tracking that discussion, so please engage there if you have opinions. Thanks!