Tune lints for 1.59 Rust

Author: tyranron

src/lib.rs

@@ -44,6 +44,7 @@
     clippy::get_unwrap,
     clippy::if_then_some_else_none,
     clippy::imprecise_flops,
+    clippy::index_refutable_slice,
     clippy::let_underscore_must_use,
     clippy::lossy_float_literal,
     clippy::map_err_ignore,