Remove unecessary clone

src/mail.rs

@@ -42,7 +42,7 @@ fn mailer() -> SmtpTransport {
 
     let smtp_client = match &CONFIG.smtp_auth_mechanism() {
         Some(auth_mechanism_json) => {
-            let auth_mechanism = serde_json::from_str::<SmtpAuthMechanism>(&auth_mechanism_json.clone());
+            let auth_mechanism = serde_json::from_str::<SmtpAuthMechanism>(&auth_mechanism_json);
             match auth_mechanism {
                 Ok(auth_mechanism) => smtp_client.authentication_mechanism(auth_mechanism),
                 Err(_) => panic!("Failure to parse mechanism. Is it proper Json? Eg. `\"Plain\"` not `Plain`"),