Fix renamed let_underscore_drop lint

    warning: lint `clippy::let_underscore_drop` has been renamed to `let_underscore_drop`
      --> generate/src/main.rs:14:5
       |
    14 |     clippy::let_underscore_drop,
       |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: use the new name: `let_underscore_drop`
       |
       = note: `#[warn(renamed_and_removed_lints)]` on by default

generate/src/main.rs

@@ -11,7 +11,6 @@
 #![allow(
     clippy::cast_lossless,
     clippy::cast_possible_truncation, // https://github.com/rust-lang/rust-clippy/issues/9613
-    clippy::let_underscore_drop,
     clippy::match_wild_err_arm,
     clippy::module_name_repetitions,
     clippy::too_many_lines,