fix(demo): fix form style in modal

修复演示页面中Modal内的Form样式问题

closed: #1076

src/views/demo/comp/modal/Modal4.vue

@@ -5,7 +5,9 @@
     title="Modal Title"
     @visible-change="handleVisibleChange"
   >
+    <div class="pt-3px pr-3px">
       <BasicForm @register="registerForm" :model="model" />
+    </div>
   </BasicModal>
 </template>
 <script lang="ts">