transform 2d demo test error

[wyli]

Describe the bug
full logs at https://github.com/Project-MONAI/MONAI/runs/2199322271?check_suite_focus=true
due to the recent PR Project-MONAI/MONAI#1836

Running ./modules/transforms_demo_2d.ipynb
Checking PEP8 compliance...
Running notebook...

Executing:   0%|          | 0/20 [00:00<?, ?cell/s]
Executing:   5%|▌         | 1/20 [00:00<00:18,  1.01cell/s]
Executing:  15%|█▌        | 3/20 [00:05<00:24,  1.43s/cell]
Executing:  20%|██        | 4/20 [00:08<00:26,  1.69s/cell]
Executing:  50%|█████     | 10/20 [00:24<00:20,  2.02s/cell]
Executing:  60%|██████    | 12/20 [00:25<00:11,  1.47s/cell]
Executing:  70%|███████   | 14/20 [00:28<00:08,  1.45s/cell]
Executing:  70%|███████   | 14/20 [00:30<00:12,  2.16s/cell]
Traceback (most recent call last):
  File "/opt/conda/bin/papermill", line 8, in <module>
    sys.exit(papermill())
  File "/opt/conda/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/opt/conda/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/opt/conda/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/opt/conda/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/opt/conda/lib/python3.8/site-packages/click/decorators.py", line 21, in new_func
    return f(get_current_context(), *args, **kwargs)
  File "/opt/conda/lib/python3.8/site-packages/papermill/cli.py", line 250, in papermill
    execute_notebook(
  File "/opt/conda/lib/python3.8/site-packages/papermill/execute.py", line 122, in execute_notebook
    raise_for_execution_errors(nb, output_path)
  File "/opt/conda/lib/python3.8/site-packages/papermill/execute.py", line 234, in raise_for_execution_errors
    raise error
papermill.exceptions.PapermillExecutionError: 
---------------------------------------------------------------------------
Exception encountered at "In [8]":
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-8-63f386481380> in <module>
     14 new_img = affine(im_data, (300, 400), mode="bilinear")
     15 new_seg = affine(seg_data, (300, 400), mode="nearest")
---> 16 print(new_img.shape, new_seg.shape)

AttributeError: 'tuple' object has no attribute 'shape'