Fix clippy warning in auth code server

Remove the redundant Arc clone in the shared authorization-code server loop.

Validation:
- cargo check -p codex-login --lib

Co-authored-by: Codex <noreply@openai.com>

codex-rs/login/src/server.rs

@@ -232,7 +232,6 @@ where
     let shutdown_notify = Arc::new(tokio::sync::Notify::new());
     let server_handle = {
         let shutdown_notify = shutdown_notify.clone();
-        let server = server.clone();
         tokio::spawn(async move {
             let result = loop {
                 tokio::select! {