demo: Update for Resolving deprecation of findDOMNode in StrictMode (#43451)

Resolving deprecation of findDOMNode in StrictMode

References: https://github.com/react-grid-layout/react-draggable/blob/master/CHANGELOG.md#440-may-12-2020

Signed-off-by: kookieaz <yunhe9337@gmail.com>

components/modal/demo/modal-render.tsx

@@ -71,6 +71,7 @@ const App: React.FC = () => {
           <Draggable
             disabled={disabled}
             bounds={bounds}
+            nodeRef={draggleRef}
             onStart={(event, uiData) => onStart(event, uiData)}
           >
             <div ref={draggleRef}>{modal}</div>