Fails to start due to "'ElementTree' object has no attribute 'getiterator'"

Hi,

this is on Debian testing with the latest available version of Pasaffe (0.56), so this is/will likely also become relevant for hirsute.

Pasaffe fails to start due to the recent update to Python 3.9 (and the changes to the etree interface):

$ pasaffe
Traceback (most recent call last):
  File "/usr/bin/pasaffe", line 46, in <module>
    pasaffe.main()
  File "/usr/lib/python3/dist-packages/pasaffe/__init__.py", line 70, in main
    window = PasaffeWindow.PasaffeWindow(database=options.filename)
  File "/usr/lib/python3/dist-packages/pasaffe/PasaffeWindow.py", line 60, in __new__
    builder = get_builder('PasaffeWindow')
  File "/usr/lib/python3/dist-packages/pasaffe_lib/helpersgui.py", line 42, in get_builder
    builder.add_from_file(ui_filename)
  File "/usr/lib/python3/dist-packages/pasaffe_lib/Builder.py", line 86, in add_from_file
    ele_widgets = tree.getiterator("object")
AttributeError: 'ElementTree' object has no attribute 'getiterator'

I have switched to PasswordSafe for now, but Pasaffe is simpler, cleaner and more convenient to use. Thanks for your work!