clear up some warnings in tests.

tests/doc_tests.rs

@@ -1,4 +1,5 @@
 #![allow(clippy::disallowed_names)]
+#![allow(dead_code)]
 
 //! Cargo miri doesn't run doctests yet, so we duplicate these here. It's
 //! probably not that important to sweat keeping these perfectly up to date, but

tests/std_tests.rs

@@ -1,4 +1,5 @@
 #![allow(clippy::uninlined_format_args)]
+#![allow(unused_imports)]
 //! The integration tests seem to always have `std` linked, so things that would
 //! depend on that can go here.