catfish doesn't run on python 3.9 [Debian sid]

Traceback (most recent call last):
  File "/usr/bin/catfish", line 44, in <module>
    catfish.main()
  File "/usr/lib/python3/dist-packages/catfish/__init__.py", line 78, in main
    window = CatfishWindow.CatfishWindow()
  File "/usr/lib/python3/dist-packages/catfish_lib/Window.py", line 171, in __new__
    builder = get_builder(__builder__['ui_file'])
  File "/usr/lib/python3/dist-packages/catfish_lib/helpers.py", line 109, in get_builder
    builder.add_from_file(ui_filename)
  File "/usr/lib/python3/dist-packages/catfish_lib/Builder.py", line 87, in add_from_file
    ele_widgets = tree.getiterator("object")
AttributeError: 'ElementTree' object has no attribute 'getiterator'

Solution:

tree.getiterator() has been deprecated since Python 2.7, and has been removed in Python 3.9. Replace all instances of tree.getiterator(tag) with tree.iter(tag)