Doesn't work with Python 3.14 (after PEP-649)

[lemenkov]

Fails to pass the tests after python/cpython#119361 merged (see commit python/cpython@9b8611e):

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ERROR: test_abc (__main__.Tests.test_abc)
Test subclassing a class with metaclass=ABCMeta. This once caused a weird Attribute Error
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Traceback (most recent call last):
  File "/home/petro/work/dataclassy/./tests.py", line 76, in setUp
    self.b = self.Beta(1, 2, 3)
             ~~~~~~~~~^^^^^^^^^
TypeError: Beta() takes no arguments
...
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Ran 33 tests in 0.037s

FAILED (errors=33)