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);