Example script fails with newer Pillow

[ja2-derek]

Getting an error trying to run to_sti_8bit.py:

~/Workspace/ja2-open-toolset/examples$ python3 to_sti_8bit.py /mnt/d/Games/JA2Classic/mods/unfinished-business/Data/loadscreens/MM24Background.sti
Traceback (most recent call last):
  File "to_sti_8bit.py", line 63, in <module>
    main()
  File "to_sti_8bit.py", line 58, in main
    images = [Image.open(file) for file in args.files]
  File "to_sti_8bit.py", line 58, in <listcomp>
    images = [Image.open(file) for file in args.files]
  File "/home/derek/.local/lib/python3.6/site-packages/PIL/Image.py", line 2881, in open
    im = _open_core(fp, filename, prefix)
  File "/home/derek/.local/lib/python3.6/site-packages/PIL/Image.py", line 2867, in _open_core
    im = factory(fp, filename)
  File "/home/derek/.local/lib/python3.6/site-packages/PIL/ImageFile.py", line 107, in __init__
    self._open()
  File "/mnt/d/Workspace/ja2-open-toolset/ja2py/fileformats/Sti.py", line 486, in _open
    self.size = (header['width'], header['height'])
AttributeError: can't set attribute

I guess something has changed in newer version of Pillow. It seems to work after downgrading with pip3 install Pillow==4.1.0