fix: 修復網站壓縮後，mermaid 會無法生成顯示的Bugs

feat： Valine 增加 option 設置

scripts/helpers/related_post.js

@@ -71,7 +71,7 @@ hexo.extend.helper.register('related_posts', function (currentPost, allPosts) {
         lazySrc +
         '="' +
         this.url_for(cover) +
-        '">'
+        '" alt="cover">'
       if (dateType === 'created') {
         result +=
           '<div class="content is-center"><div class="date"><i class="far fa-calendar-alt fa-fw"></i>' +