Remove unittest.makeSuite, gone from Python 3.13

See https://docs.python.org/3.13/whatsnew/3.13.html

"""
Removed the following unittest functions, deprecated in Python 3.11:

    unittest.findTestCases()
    unittest.makeSuite()
    unittest.getTestCaseNames()
"""

The removed call does not seem to have any effect when the file is executed
directly, run trough unittest discover or pytest.

tests/test_invalid_binary.py

@@ -69,6 +69,3 @@ def test_invalid_binary(self):
 
 if __name__ == '__main__':
     unittest.main()
-
-suite = unittest.makeSuite(InvalidBinaryChars,'test')
-