替换数组startTime的值：

原数据

	this.serviceTimeList.push({serviceTimeName: '服务时间段',startTime: this.startTime,endTime: this.endTime,currentDateStart: this.currentDate,currentDateEnd: this.currentDate})

this.$set(this.array, index, newValue);

this.$set(this.serviceTimeList[index], 'startTime', this.startTime);