chore(ui): fix demo of select loading

Author: xiejay97

packages/ui/src/components/select/demos/5.Loading.md

@@ -77,7 +77,7 @@ export default function Demo() {
             setLoading2(false);
             setList2((draft) => {
               draft.push(
-                Array.from({ length: 20 }).map((_, index) => ({
+                ...Array.from({ length: 20 }).map((_, index) => ({
                   label: `Item ${index + draft.length}`,
                   value: index + draft.length,
                 }))