[BUG] [Python 3.12] py35_asyncio_async_def raises RuntimeError: There is no current event loop in thread 'MainThread'.

[hroncok]

Describe the bug

We have this test failure in Fedora with Python 3.12.0a3:

Traceback (most recent call last):
  File "/builddir/build/BUILD/cython-0.29.32/TEST_TMP/0/run/py35_asyncio_async_def/main.py", line 9, in <module>
    with closing(asyncio.get_event_loop()) as loop:
                 ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/asyncio/events.py", line 676, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'MainThread'.

This is from 0.29.32 but I see the same code in the master branch:

cython/tests/run/py35_asyncio_async_def.srctree

Line 28 in b2cad76

with closing(asyncio.get_event_loop()) as loop:

Code to reproduce the behaviour:

Run tests with Python 3.12.0a3.

Expected behaviour

Tests pass.

Environment

OS: Fedora Linux
Python version: 3.12.0a3
Cython version: 0.29.32 or master branch

Additional context

https://docs.python.org/3.12/whatsnew/3.12.html#changes-in-the-python-api

asyncio.get_event_loop() and many other asyncio functions like ensure_future(), shield() or gather(), and also the get_event_loop() method of BaseDefaultEventLoopPolicy now raise a RuntimeError if called when there is no running event loop and the current event loop was not set. Previously they implicitly created and set a new current event loop. DeprecationWarning is no longer emitted if there is no running event loop but the current event loop is set in the policy. (Contributed by Serhiy Storchaka in gh-93453.)

[scoder]

Closed in #5188