Fix Clippy for Rust 1.90 beta (#7826)

Fix Clippy for recently released Rust 1.90 beta. There may be more changes required when Rust 1.89 stable is released in a few days, but possibly not 🤞

beacon_node/http_api/tests/tests.rs

@@ -6270,7 +6270,9 @@ impl ApiTester {
 
         // Produce a BLS to execution change event
         self.client
-            .post_beacon_pool_bls_to_execution_changes(&[self.bls_to_execution_change.clone()])
+            .post_beacon_pool_bls_to_execution_changes(std::slice::from_ref(
+                &self.bls_to_execution_change,
+            ))
             .await
             .unwrap();