add transition for select

style/components/select.less

@@ -59,6 +59,8 @@
     background-color: #fff;
     border-radius: 6px;
     border: 1px solid #d9d9d9;
+    .transition(all .3s @ease-in-out);
+
     &:hover {
       border-color: #23c0fa;
     }