update src/components/Dialog/src/Dialog.vue.

解决了单独使用elementplus diaolog组件时，样式被篡改的问题


Signed-off-by: AKING <2734339436@qq.com>
(cherry picked from commit cba35d698f)

src/components/Dialog/src/Dialog.vue

@@ -66,6 +66,7 @@ const dialogStyle = computed(() => {
     lock-scroll
     draggable
     top="0"
+    class="com-dialog"
     :show-close="false"
   >
     <template #header="{ close }">
@@ -106,6 +107,7 @@ const dialogStyle = computed(() => {
 </template>
 
 <style lang="scss">
+.com-dialog {
   .#{$elNamespace}-overlay-dialog {
     display: flex;
     justify-content: center;
@@ -134,4 +136,5 @@ const dialogStyle = computed(() => {
       top: 0;
     }
   }
+}
 </style>