Drop 32bit-related setup from the CI setup and README
Use dtolnay/rust-toolchain action instead of unmaintained action-rs/toolchain action
For point 1, I think we don't care much about the backward-compatibility with that old version. That said, it should be good to test against multiple R versions, so I included point 2, but this is optional.
This pull request does:
For point 1, I think we don't care much about the backward-compatibility with that old version. That said, it should be good to test against multiple R versions, so I included point 2, but this is optional.