Docstring of __weakref__ in Python has changed - test_autodoc_default_options and test_autodoc_default_options_with_values rely on that

[befeleme]

Describe the bug

Sphinx 7.2.6 test_autodoc_default_options fails with Python 3.13.0~a2. The change was backported to Python 3.12 and Python 3.11 branches: python/cpython#112266, so it'll be soon in all three Pythons.
I attempted to fix the test lured by the obviousness of the failure but realised that it's not so easy given version matrix (#11774).

=================================== FAILURES ===================================
_________________________ test_autodoc_default_options _________________________

app = <SphinxTestApp buildername='html'>

    @pytest.mark.sphinx('html', testroot='ext-autodoc')
    def test_autodoc_default_options(app):
        # no settings
        actual = do_autodoc(app, 'class', 'target.enums.EnumCls')
        assert '   .. py:attribute:: EnumCls.val1' not in actual
        assert '   .. py:attribute:: EnumCls.val4' not in actual
        actual = do_autodoc(app, 'class', 'target.CustomIter')
        assert '   .. py:method:: target.CustomIter' not in actual
        actual = do_autodoc(app, 'module', 'target')
        assert '.. py:function:: function_to_be_imported(app)' not in actual
    
        # with :members:
        app.config.autodoc_default_options = {'members': None}
        actual = do_autodoc(app, 'class', 'target.enums.EnumCls')
        assert '   .. py:attribute:: EnumCls.val1' in actual
        assert '   .. py:attribute:: EnumCls.val4' not in actual
    
        # with :members: = True
        app.config.autodoc_default_options = {'members': None}
        actual = do_autodoc(app, 'class', 'target.enums.EnumCls')
        assert '   .. py:attribute:: EnumCls.val1' in actual
        assert '   .. py:attribute:: EnumCls.val4' not in actual
    
        # with :members: and :undoc-members:
        app.config.autodoc_default_options = {
            'members': None,
            'undoc-members': None,
        }
        actual = do_autodoc(app, 'class', 'target.enums.EnumCls')
        assert '   .. py:attribute:: EnumCls.val1' in actual
        assert '   .. py:attribute:: EnumCls.val4' in actual
    
        # with :special-members:
        # Note that :members: must be *on* for :special-members: to work.
        app.config.autodoc_default_options = {
            'members': None,
            'special-members': None,
        }
        actual = do_autodoc(app, 'class', 'target.CustomIter')
        assert '   .. py:method:: CustomIter.__init__()' in actual
        assert '      Create a new `CustomIter`.' in actual
        assert '   .. py:method:: CustomIter.__iter__()' in actual
        assert '      Iterate squares of each value.' in actual
        if not IS_PYPY:
            assert '   .. py:attribute:: CustomIter.__weakref__' in actual
>           assert '      list of weak references to the object (if defined)' in actual
E           AssertionError: assert '      list of weak references to the object (if defined)' in StringList(['', '.. py:class:: CustomIter()', '   :module: target', '', '', '   .. py:method:: CustomIter.__init__()',... 0), ('/tmp/pytest-of-mockbuild/pytest-0/ext-autodoc/target/__init__.py:docstring of target.CustomIter.snafucate', 1)])

tests/test_ext_autodoc_configs.py:1630: AssertionError

How to Reproduce

Run tests with Python 3.13.0~a2

Environment Information

Sphinx 7.2.6

Sphinx extensions

No response

Additional context

No response

[picnixz]

I am aware of this issue and its corresponding PR. It will probably be the first PR to be merged when we'll resume active development since it blocks the CI