fix: add missing tracing::warn import in update.rs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

core/archipelago/src/update.rs

@@ -5,7 +5,7 @@ use chrono::Timelike;
 use serde::{Deserialize, Serialize};
 use std::path::Path;
 use tokio::fs;
-use tracing::{debug, info};
+use tracing::{debug, info, warn};
 
 const DEFAULT_UPDATE_MANIFEST_URL: &str =
     "https://raw.githubusercontent.com/archipelago-os/releases/main/manifest.json";