Update CI toolchain to stable by moreal · Pull Request #4051 · RustPython/RustPython

Currently, the cargo clippy or the CI Check Rust code with rustfmt and clippy job failed.
It warns clippy::derive_partial_eq_without_eq as unknown lints but it exists in 1.63.0 release. You can see it through https://rust-lang.github.io/rust-clippy/master/.

At the #4046, it updated the toolchain's version to 1.62.1 from stable and the stable version was 1.63.0.

But I see the pull request description while writing this pull request's description:

I need time to check if the failure is our bug or rust regression.

I don't know its context so it may be intended and if then, this pull request should be closed.