tzname_widget broken under Python3

[tseaver]

Cannot add or edit a prinicpal, because:

...
  File "mapping_item_6251f2e4a314675b630112ec7f5df3b9.py", line 465, in render
  File "/home/tseaver/projects/byelizabeth/substanced-buildout/eggs/deform-2.0.15-py3.11.egg/deform/field.py", line 626, in serialize
    return self.widget.serialize(**values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/tseaver/projects/byelizabeth/substanced-buildout/eggs/deform-2.0.15-py3.11.egg/deform/widget.py", line 1167, in serialize
    raise TypeError(e)
TypeError: Values must be a sequence type (list, tuple, or range).

values in this case is the result calling zip(_ZONES, _ZONES), which returns an instance of the builtin type zip: not one of the "allowed" value types for deform.widget.SelectWidget.serialize (must be list, tuple, or range).