Remove msrv field from .clippy.toml
Remove msrv field from .clippy.toml

Since Rust 1.64, Clippy respects `rust-version` field in Cargo.toml.
https://github.com/rust-lang/rust/commit/b776fb82941cadfc752368901f210831d5184d95

crossbeam-rs/crossbeam,crossbeam-rs/crossbeam,crossbeam-rs/crossbeam,crossbeam-rs/crossbeam