tink-proto: remove warning suppression

The rustdoc::bare_urls warning is only available in Rust >= 1.53,
so building with earlier Rust versions complains that the lint
is unrecognized.

Author: daviddrysdale

proto/src/lib.rs

@@ -17,7 +17,6 @@
 //! Protocol buffer message definitions for Tink.
 
 #![deny(broken_intra_doc_links)]
-#![allow(rustdoc::bare_urls)]
 
 #[cfg(not(feature = "json"))]
 include!("codegen/google.crypto.tink.rs");