fix export

Author: lohanidamodar

templates/dart/lib/package.dart.twig

@@ -8,7 +8,9 @@ import 'src/service.dart';
 import 'src/input_file.dart';
 import 'src/upload_progress.dart';
 import 'models.dart' as models;
+
 export 'src/response.dart';
+export 'src/client.dart';
 export 'src/exception.dart';
 export 'src/input_file.dart';
 export 'src/upload_progress.dart';