Discussion: Use unstable rust to run ci tool.

[liurenjie1024]

Currently iceberg-rust requires stable rust to build, which is reasonable as a library. But ci tools such as cargo fmt, cargo clippy are only used during ci or local development, and will not force downstream application/libary to use unstable rust. Some advanced features of these tools are only available in unstable rust, so I would propose to use unstable rust to run these tools.

[Xuanwo]

I propose using the exact same nightly toolchain date as the stable Rust release in our rust-toolchain file. For example, if Rust 1.79 is released on 2024-06-13, we will use nightly-2024-06-13 for our development toolchain.

So we will have the same code (nearly) as stable rust, but also allow us to use nightly options.

[liurenjie1024]

I propose using the exact same nightly toolchain date as the stable Rust release in our rust-toolchain file. For example, if Rust 1.79 is released on 2024-06-13, we will use nightly-2024-06-13 for our development toolchain.

So we will have the same code (nearly) as stable rust, but also allow us to use nightly options.

+1 for this.

[liurenjie1024]

I'm happy to take this.