Rust 1.89 expands x86 support, stabilizes APIs, and downgrades macOS x86_64 support

Rust 1.89 is now released, expanding x86 and x86/x86_64 platform support with new processor instructions and features, including additional AVX-512 intrinsics. The target_feature attribute adds support for SHA512, SM3, SM4, KL, and WIDEKL, giving developers better access to modern CPU capabilities directly from Rust code.

Full changelog: https://blog.rust-lang.org/2025/08/07/Rust-1.89.0/