DatePicker : type="monthrange" 关闭选择面板选择状态不重置的bug

月范围选择面板中选择了一项后，点击其他区域失焦关闭面板，再打开时已选择一项的状态并没有重置

packages/date-picker/src/panel/month-range.vue

@@ -279,6 +279,7 @@
         // NOTE: this is a hack to reset {min, max}Date on picker open.
         // TODO: correct way of doing so is to refactor {min, max}Date to be dependent on value and internal selection state
         //       an alternative would be resetView whenever picker becomes visible, should also investigate date-panel's resetView
+        if (this.minDate && this.maxDate == null) this.rangeState.selecting = false;
         this.minDate = this.value && isDate(this.value[0]) ? new Date(this.value[0]) : null;
         this.maxDate = this.value && isDate(this.value[0]) ? new Date(this.value[1]) : null;
       }