Fix clippy's performance lints (#1286)

* Fix clippy perf lints

* Cargo fmt

* Add  and  to lint rule in Makefile

* Fix some leftover clippy lints

crypto/eth2_keystore/src/keystore.rs

@@ -190,7 +190,7 @@ impl Keystore {
 
         let keypair = keypair_from_secret(plain_text.as_bytes())?;
         // Verify that the derived `PublicKey` matches `self`.
-        if keypair.pk.as_hex_string()[2..].to_string() != self.json.pubkey {
+        if keypair.pk.as_hex_string()[2..] != self.json.pubkey {
             return Err(Error::PublicKeyMismatch);
         }