Merge pull request #3774 from doctrine/Fix2.9-Tests

GH-3776 Fix RunSqlCommand deprecation notice with Symfony Console 4.4+ 

lib/Doctrine/DBAL/Tools/Console/Command/RunSqlCommand.php

@@ -64,5 +64,7 @@ EOT
         }
 
         $output->write(Dumper::dump($resultSet, (int) $depth));
+
+        return 0;
     }
 }