fix: resolve issue with code input can not displaying fullscreen in modal component (#6787)

#### What type of PR is this?

/area ui
/kind bug
/milestone 2.20.x

#### What this PR does / why we need it:

修复 Code 输入框在模态框（VModal）组件中无法正常全屏显示的问题。

#### Which issue(s) this PR fixes:

Fixes https://github.com/halo-dev/halo/issues/6682

#### Does this PR introduce a user-facing change?

```release-note
修复 Code 输入框在模态框（VModal）组件中无法正常全屏显示的问题。
```

ui/packages/components/src/components/modal/Modal.vue

@@ -156,7 +156,7 @@ watch(
         <div
           v-show="internalVisible"
           :style="contentStyles"
-          class="modal-content transform transition-all duration-300"
+          class="modal-content transition-all duration-300"
           :class="{ 'modal-focus': focus }"
         >
           <div v-if="$slots.header || title" class="modal-header group">