[issue43234] Prohibit passing non-ThreadPoolExecutor executors to loop.set_default_executor following a deprecation

[Serhiy Storchaka]

Change by Serhiy Storchaka <storchaka+cpython at gmail.com>:


----------
versions: +Python 3.11 -Python 3.10

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue43234>
_______________________________________