The 1.64.0 pre-release is ready for testing. The release is scheduled for September 22. 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
You can leave feedback on the internals thread.
The release team is also thinking about changes to our pre-release process: we'd love your feedback on this GitHub issue.