fix(module: date-picker): popup animation (#146)

components/date-picker/DatePicker.razor

@@ -9,6 +9,8 @@
                     Disabled="Disabled"
                     PopupContainerSelector="@PopupContainerSelector"
                     OnVisibleChange="visible => AutoFocus = visible"
+                    OverlayEnterCls="slide-up-enter slide-up-enter-active slide-up"
+                    OverlayLeaveCls="slide-up-leave slide-up-leave-active slide-up"
                     Trigger="new TriggerType[] { TriggerType.Click }">
         <Overlay>
             <div class="@(PrefixCls)-panel-container">