Komifloのメタデータに有効期限を設定する

app/MetadataResolver/KomifloResolver.php

@@ -22,6 +22,7 @@ class KomifloResolver implements Resolver
                 ' - ' .
                 ($json['content']['parents'][0]['data']['title'] ?? '?');
             $metadata->image = $json['content']['cdn_public'] . "/564_mobile_large_3x/" . $json['content']['named_imgs']['cover']['filename'] . $json['content']['signature'];
+            $metadata->expires_at = date('Y-m-d H:i:s', strtotime($json['content']['signature_expires']));
 
             return $metadata;
         } else {