chore: use more representative size check code

packages/size-check/src/index.ts

@@ -1,4 +1,6 @@
-import { render, createVNode } from '@vue/runtime-dom'
+import { h, createApp } from '@vue/runtime-dom'
 
 // The bare minimum code required for rendering something to the screen
-render(createVNode('div'), document.getElementById('app')!)
+createApp({
+  render: () => h('div', 'hello world!')
+}).mount('#app')