Avoids moving warnings into errors

Allows avoiding breaking compilation if new warnings are enabled

src/lib.rs

@@ -1,14 +1,5 @@
 #![doc = include_str!("../README.md")]
-#![deny(
-    future_incompatible,
-    nonstandard_style,
-    rust_2018_idioms,
-    missing_copy_implementations,
-    trivial_casts,
-    trivial_numeric_casts,
-    unsafe_code,
-    unused_qualifications
-)]
+#![deny(unsafe_code)]
 
 use std::borrow::{Borrow, Cow};
 use std::cmp::Ordering;