fix: saving an post causes the publish time to be lost (#807)

#### What type of PR is this?

/kind bug

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

修复保存文章设置导致发布时间丢失的问题。

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

Fixes https://github.com/halo-dev/halo/issues/3080

#### Special notes for your reviewer:

测试方式：

1. 创建若干文章。
2. 返回到文章管理列表。
3. 打开任意文章的设置。
4. 检查发布时间是否回显，然后保存。
5. 保存之后检查发布时间是否还存在。

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

```release-note
修复 Console 端保存文章设置导致发布时间丢失的问题。
```

src/modules/contents/pages/components/SinglePageSettingModal.vue

@@ -370,7 +370,7 @@ const onPublishTimeChange = (value: string) => {
               type="select"
             ></FormKit>
             <FormKit
-              :value="publishTime"
+              :model-value="publishTime"
               label="发表时间"
               type="datetime-local"
               name="publishTime"

src/modules/contents/posts/components/PostSettingModal.vue

@@ -344,7 +344,7 @@ const annotationsFormRef = ref<InstanceType<typeof AnnotationsForm>>();
               type="select"
             ></FormKit>
             <FormKit
-              :value="publishTime"
+              :model-value="publishTime"
               label="发表时间"
               type="datetime-local"
               @input="onPublishTimeChange"