Minor update (#1460)

- 后台上传设置增加 avif 类型
- 后台 Avatar 头像支持原生懒加载

var/Widget/Base/Comments.php

@@ -289,7 +289,7 @@ class Comments extends Base implements QueryInterface
             Comments::pluginHandle()->trigger($plugged)->gravatar($size, $rating, $default, $this);
             if (!$plugged) {
                 $url = Common::gravatarUrl($this->mail, $size, $rating, $default, $this->request->isSecure());
-                echo '<img class="avatar" src="' . $url . '" alt="' .
+                echo '<img class="avatar" loading="lazy" src="' . $url . '" alt="' .
                     $this->author . '" width="' . $size . '" height="' . $size . '" />';
             }
         }

var/Widget/Options/General.php

@@ -272,7 +272,7 @@ class General extends Options implements ActionInterface
         }
 
         $attachmentTypesOptions = [
-            '@image@' => _t('图片文件') . ' <code>(gif jpg jpeg png tiff bmp webp)</code>',
+            '@image@' => _t('图片文件') . ' <code>(gif jpg jpeg png tiff bmp webp avif)</code>',
             '@media@' => _t('多媒体文件') . ' <code>(mp3 mp4 mov wmv wma rmvb rm avi flv ogg oga ogv)</code>',
             '@doc@'   => _t('常用档案文件') . ' <code>(txt doc docx xls xlsx ppt pptx zip rar pdf)</code>',
             '@other@' => _t(