fix: ui issue caused by too long parent category selection list in new category (#577)

* Update AttachmentTab.vue

* Update option.js

* Update src/views/system/optiontabs/AttachmentTab.vue

Co-authored-by: Ryan Wang <i@ryanc.cc>

* revert

* revert

* Add scroll bar when category tree is too large

Co-authored-by: Ryan Wang <i@ryanc.cc>

src/components/Category/CategorySelectTree.vue

@@ -7,6 +7,7 @@
     placeholder="请选择上级目录，默认为顶级目录"
     treeDefaultExpandAll
     @change="handleChange"
+    :dropdown-style="{ overflow: 'auto' }"
   >
   </a-tree-select>
 </template>