i128/u128 haven't flagged `improper_ctypes` for a while, and this just made it to stable [1]. Remove the `allow`s as they are no longer needed. [1]: https://blog.rust-lang.org/2025/08/07/Rust-1.89.0/#i128-and-u128-in-extern-c-functions
i128/u128 haven't flagged `improper_ctypes` for a while, and this just made it to stable [1]. Remove the `allow`s as they are no longer needed. [1]: https://blog.rust-lang.org/2025/08/07/Rust-1.89.0/#i128-and-u128-in-extern-c-functions