fix(VRipple): avoiding more and more

[dgmpk]

In some cases, when calling show continuously, ripples will increase.

Description

If import @vant/touch emulator, ripples will increase when trigger mousedown.

Markup:

<script>
import '@vant/touch-emulator' // for vant.js
</script>

<template>
<v-btn>Click here</v-btn>
</template>