Test failure with Python 3.10

[fabaff]

Some tests are failing with Python 3.10.

============================= test session starts ==============================
platform linux -- Python 3.10.1, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: /build/aspell-python-py3-1.15
collected 17 items                                                             

test/unittests.py ..........FFF..s.                                      [100%]

=================================== FAILURES ===================================
________________________ TestPersonalwordlist.test_add _________________________

self = <unittests.TestPersonalwordlist testMethod=test_add>

    def test_add(self):
        "addtoPersonal"
    
        for word in self.polish_words:
                self.assertFalse(self.speller.check(word))
    
        for word in self.polish_words:
>               self.speller.addtoPersonal(word)
E     TypeError: a string is required

test/unittests.py:174: TypeError
________________________ TestPersonalwordlist.test_get _________________________

self = <unittests.TestPersonalwordlist testMethod=test_get>

    def test_get(self):
        "getPersonalwordlist"
    
        pwl = self.speller.getPersonalwordlist()
        self.assertEqual(set(pwl), set())
    
        for word in self.polish_words:
>               self.speller.addtoPersonal(word)
E     TypeError: a string is required

test/unittests.py:186: TypeError
______________________ TestPersonalwordlist.test_saveall _______________________

self = <unittests.TestPersonalwordlist testMethod=test_saveall>

    def test_saveall(self):
        "saveAllwords"
    
        for word in self.polish_words:
>               self.speller.addtoPersonal(word)
E     TypeError: a string is required

test/unittests.py:195: TypeError
=========================== short test summary info ============================
FAILED test/unittests.py::TestPersonalwordlist::test_add - TypeError: a strin...
FAILED test/unittests.py::TestPersonalwordlist::test_get - TypeError: a strin...
FAILED test/unittests.py::TestPersonalwordlist::test_saveall - TypeError: a s...
=================== 3 failed, 13 passed, 1 skipped in 0.48s ====================