[ci]: Setup rust as pre run & allow deadcode

[milosbackonja]

No description provided.

[GraDKh]

It's weird, but when I'm running the clippy command locally it doesn't pass:

cargo clippy --all --all-features --tests --benches --examples -- -D warnings

This is actually because we have a feature stable_only with which we currently can't compile all the crate. I suppose we shouldn't run clippy with --all-features and pick some reasonable subset