chore: bump version to 3.9.0-2 for second test release

- Update version in package.json, Cargo.toml, tauri.conf.json
- Fix clippy too_many_arguments warning in forwarder.rs

src-tauri/src/proxy/forwarder.rs

@@ -34,6 +34,7 @@ pub struct RequestForwarder {
 }
 
 impl RequestForwarder {
+    #[allow(clippy::too_many_arguments)]
     pub fn new(
         router: Arc<ProviderRouter>,
         timeout_secs: u64,