Fix renamed let_underscore_drop lint
Fix renamed let_underscore_drop lint

    warning: lint `clippy::let_underscore_drop` has been renamed to `let_underscore_drop`
       --> src/lib.rs:150:5
        |
    150 |     clippy::let_underscore_drop,
        |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `let_underscore_drop`
        |
        = note: `#[warn(renamed_and_removed_lints)]` on by default

dtolnay/serde-yaml