Fixing fuzzy tests

Author: dr-orlovsky

src/key.rs

@@ -668,7 +668,7 @@ mod test {
         let s = Secp256k1::new();
         let (sk, _) = s.generate_keypair(&mut DumbRng(0));
 
-        #[cfg(feature = "bitcoin_hashes")]
+        #[cfg(all(feature = "bitcoin_hashes", not(fuzzing)))]
         assert_eq!(&format!("{:?}", sk),
                    "SecretKey(#73e200e2...29d234a4)");
         #[cfg(all(not(feature = "bitcoin_hashes"), any(feature = "std", feature = "alloc")))]