Remove the lint unused_crate_dependencies as it is giving false positives

`unused_crate_dependencies` is complaining about the `rand`
dev-dependency, which is used by integ tests. This is a known problem
with this lint: rust-lang/rust#57274

Author: andreacorbellini

src/lib.rs

@@ -163,7 +163,6 @@
 #![warn(missing_docs)]
 #![warn(pointer_structural_match)]
 #![warn(unreachable_pub)]
-#![warn(unused_crate_dependencies)]
 #![warn(unused_qualifications)]
 
 mod iter;