chore: remove the import of vitest

Author: Alfred-Skyblue

packages/runtime-core/__tests__/apiWatch.spec.ts

@@ -32,10 +32,9 @@ import {
   effectScope,
   toRef
 } from '@vue/reactivity'
-import { expect } from 'vitest'
 
 // reference: https://vue-composition-api-rfc.netlify.com/api.html#watch
-
+// 移除 vitest 的导入
 describe('api: watch', () => {
   it('effect', async () => {
     const state = reactive({ count: 0 })