BUG: Add missing enumerate with multi-ndarray-output itk filters

Required for returning the (registered_image, transform_parameters)
output when ndarray's is passed for the fixed and moving image in
itk-elastix.

Wrapping/Generators/Python/itkHelpers.py

@@ -98,7 +98,7 @@ def image_filter_wrapper(*args, **kwargs):
             output = image_filter(*tuple(args_list), **kwargs)
             if isinstance(output, tuple):
                 output_list = list(output)
-                for index, value in output_list:
+                for index, value in enumerate(output_list):
                     if isinstance(value, itk.Image):
                         if have_xarray_input:
                             data_array = itk.xarray_from_image(value)