lang/rust: Update to 1.91.1

• Drop WASM option as it requires llvm from ports it was probably broken since it was introduced and no one noticed / used it

Announce: https://blog.rust-lang.org/2025/10/30/Rust-1.91.0/

		https://blog.rust-lang.org/2025/11/10/Rust-1.91.1/

ChangeLog: https://github.com/rust-lang/rust/releases/tag/1.91.0

		https://github.com/rust-lang/rust/releases/tag/1.91.1

PR: 290816
Tested by: mikael,pkubaj