Update signature.rs

src/signature.rs

@@ -1,5 +1,6 @@
 //! The `signature` module provides functionality for public, and private keys.
 
+use generic_array::GenericArray;
 use generic_array::typenum::{U32, U64};
 use rand::{ChaChaRng, Rng, SeedableRng};
 use ring::error::Unspecified;