Segmentation fault on signal disconnect after module reload

[bers at gmx.net]

Hi,
I managed to reproduce a segmentation fault in PyQt.

This is bug.py:
```
from importlib import reload
from pathlib import Path


def test_reload() -> None:
    mod_folder = Path("mod_folder")
    mod_folder.mkdir(exist_ok=True)

    with open(mod_folder / "mod_file.py", "w") as f:
        f.write("from PyQt6.QtCore import QObject, pyqtSignal, pyqtSlot\n")
        f.write("class Class(QObject):\n")
        f.write("    signal = pyqtSignal()\n")
        f.write("    @pyqtSlot()\n")  # <-- this line crashes, try removing it!
        f.write("    def slot(self): ...")

    from mod_folder import mod_file

    instance = mod_file.Class()
    instance.signal.connect(instance.slot)

    reload(mod_file)
    instance.__class__ = mod_file.Class

    instance.signal.disconnect(instance.slot)
```

Python 3.12.4 on Windows 11
pip install pytest==8.3.2 PyQt6==6.7.1
pytest bug.py

Context: https://github.com/pyqtgraph/pyqtgraph/pull/3123#issuecomment-2284538600

Stack trace:

```
bug.py Windows fatal exception: access violation

Current thread 0x000049bc (most recent call first):
  File "C:\Code\bug.py", line 24 in test_reload
  File "C:\Code\.venv\Lib\site-packages\_pytest\python.py", line 159 in pytest_pyfunc_call
  File "C:\Code\.venv\Lib\site-packages\pluggy\_callers.py", line 103 in _multicall
  File "C:\Code\.venv\Lib\site-packages\pluggy\_manager.py", line 120 in _hookexec
  File "C:\Code\.venv\Lib\site-packages\pluggy\_hooks.py", line 513 in __call__
  File "C:\Code\.venv\Lib\site-packages\_pytest\python.py", line 1627 in runtest
  File "C:\Code\.venv\Lib\site-packages\_pytest\runner.py", line 174 in pytest_runtest_call
  File "C:\Code\.venv\Lib\site-packages\pluggy\_callers.py", line 103 in _multicall
  File "C:\Code\.venv\Lib\site-packages\pluggy\_manager.py", line 120 in _hookexec
  File "C:\Code\.venv\Lib\site-packages\pluggy\_hooks.py", line 513 in __call__
  File "C:\Code\.venv\Lib\site-packages\_pytest\runner.py", line 242 in <lambda>
  File "C:\Code\.venv\Lib\site-packages\_pytest\runner.py", line 341 in from_call
  File "C:\Code\.venv\Lib\site-packages\_pytest\runner.py", line 241 in call_and_report
  File "C:\Code\.venv\Lib\site-packages\_pytest\runner.py", line 132 in runtestprotocol
  File "C:\Code\.venv\Lib\site-packages\_pytest\runner.py", line 113 in pytest_runtest_protocol
  File "C:\Code\.venv\Lib\site-packages\pluggy\_callers.py", line 103 in _multicall
  File "C:\Code\.venv\Lib\site-packages\pluggy\_manager.py", line 120 in _hookexec
  File "C:\Code\.venv\Lib\site-packages\pluggy\_hooks.py", line 513 in __call__
  File "C:\Code\.venv\Lib\site-packages\_pytest\main.py", line 362 in pytest_runtestloop
  File "C:\Code\.venv\Lib\site-packages\pluggy\_callers.py", line 103 in _multicall
  File "C:\Code\.venv\Lib\site-packages\pluggy\_manager.py", line 120 in _hookexec
  File "C:\Code\.venv\Lib\site-packages\pluggy\_hooks.py", line 513 in __call__
  File "C:\Code\.venv\Lib\site-packages\_pytest\main.py", line 337 in _main
  File "C:\Code\.venv\Lib\site-packages\_pytest\main.py", line 283 in wrap_session
  File "C:\Code\.venv\Lib\site-packages\_pytest\main.py", line 330 in pytest_cmdline_main
  File "C:\Code\.venv\Lib\site-packages\pluggy\_callers.py", line 103 in _multicall
  File "C:\Code\.venv\Lib\site-packages\pluggy\_manager.py", line 120 in _hookexec
  File "C:\Code\.venv\Lib\site-packages\pluggy\_hooks.py", line 513 in __call__
  File "C:\Code\.venv\Lib\site-packages\_pytest\config\__init__.py", line 175 in main
  File "C:\Code\.venv\Lib\site-packages\_pytest\config\__init__.py", line 201 in console_main
  File "c:\Code\.venv\Scripts\pytest.exe\__main__.py", line 8 in <module>
  File "<frozen runpy>", line 88 in _run_code
  File "<frozen runpy>", line 198 in _run_module_as_main
```

Kind regards