No more root file

Signed-off-by: Joas Schilling <coding@schilljs.com>

build/files-checker.php

@@ -58,7 +58,6 @@ $expectedFiles = [
 	'COPYING-README',
 	'core',
 	'cron.php',
-	'db_structure.xml',
 	'index.html',
 	'index.php',
 	'issue_template.md',