chore: avoid v-cloak test warning

Author: yyx990803

packages/runtime-dom/__tests__/directives/vCloak.spec.ts

@@ -4,7 +4,9 @@ describe('vCloak', () => {
   test('should be removed after compile', () => {
     const root = document.createElement('div')
     root.setAttribute('v-cloak', '')
-    createApp({}).mount(root)
+    createApp({
+      render() {}
+    }).mount(root)
     expect(root.hasAttribute('v-cloak')).toBe(false)
   })
 })