Taro.pageScrollTo android 防抖动

滑动到顶部时，给pageScrollTo设置个duration

const duration = this.currentIndex == undefined && index == undefined ? 200 : 0
        setTimeout(() => {
            Taro.pageScrollTo({ scrollTop: this.yPosition, duration: this.yPosition == 0 ? 50 : 0 })
        }, duration)