fix: deprecated

This was deprecated at Nextcloud 30

Signed-off-by: Vitor Mattos <vitor@php.rio>

lib/Db/SignRequestMapper.php

@@ -441,7 +441,7 @@ private function getFilesAssociatedFilesWithMeQueryBuilder(string $userId, ?arra
 		// when the database is PostgreSQL. The problem is that the command
 		// addGroupBy add quotes over all text send as argument. With
 		// PostgreSQL json columns don't have problem if not added to group by.
-		if (!$qb->getConnection()->getDatabasePlatform() instanceof PostgreSQLPlatform) {
+		if (!$qb->getConnection()->getDatabaseProvider() instanceof PostgreSQLPlatform) {
 			$qb->addGroupBy('f.metadata');
 		}