rust-version should be >= 1.85.0

[freijon]

When trying to build rio with a Rust version < 1.85.0, one gets the following error message:

• /usr/lib/rust/1.84.1/bin/cargo build --release --features wayland --features x11 --verbose --no-default-features error: rustc 1.84.1 is not supported by the following packages: [email protected] requires rustc 1.85.0 [email protected] requires rustc 1.85.0

So if the crates require a certain minimal Rust version, I think rio itself should also require this version.