chore: fix type error in playground demo

Author: posva

packages/playground/src/stores/demo-counter.ts

@@ -1,6 +1,8 @@
 import { defineStore, acceptHMRUpdate } from 'pinia'
 
 const delay = (t: number) => new Promise((r) => setTimeout(r, t))
+// just to ignore the not used error
+delay(0)
 
 export const useCounter = defineStore('demo-counter', {
   state: () => ({