docs: rust: quick-start: update Ubuntu versioned packages

docs: rust: quick-start: update Ubuntu versioned packages

Now that the minimum supported Rust version is bumped, bump the versioned
Rust packages [1][2][3][4] to that version for Ubuntu in the Quick
Start guide.

In addition, add "may" to the `RUST_LIB_SRC` line since it does not look
like it is needed from a quick test in a Ubuntu 24.04 LTS container.

Link: https://packages.ubuntu.com/search?suite=all&searchon=names&keywords=rustc
Link: https://packages.ubuntu.com/search?suite=all&searchon=names&keywords=bindgen
Link: https://launchpad.net/ubuntu/+source/rustc-1.85
Link: https://launchpad.net/ubuntu/+source/rust-bindgen-0.71
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Link: https://patch.msgid.link/20260405235309.418950-24-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>