fix(CI): Suppress psalm UndefinedClass

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

lib/private/Files/Storage/Local.php

@@ -584,6 +584,7 @@ private function calculateEtag(string $path, array $stat): string {
  }
 
  private function canDoCrossStorageMove(IStorage $sourceStorage) {
+ /** @psalm-suppress UndefinedClass */
  return $sourceStorage->instanceOfStorage(Local::class)
  // Don't treat ACLStorageWrapper like local storage where copy can be done directly.
  // Instead, use the slower recursive copying in php from Common::copyFromStorage with