Add missing Friendica\DI namespace to files (PHPStorm inspection)

src/Database/PostUpdate.php

@@ -7,6 +7,7 @@ namespace Friendica\Database;
 use Friendica\Core\Config;
 use Friendica\Core\Logger;
 use Friendica\Core\Protocol;
+use Friendica\DI;
 use Friendica\Model\Contact;
 use Friendica\Model\Item;
 use Friendica\Model\ItemURI;