[Bug]: TimerAsyncio does not work with Python 3.14 #30917

=================================== FAILURES ===================================
_________________________________ test_webagg __________________________________
[gw28] linux -- Python 3.14.2 /build/python-matplotlib/src/matplotlib/test-env/bin/python

    @pytest.mark.skipif('TF_BUILD' in os.environ,
                        reason="this test fails an azure for unknown reasons")
    @pytest.mark.skipif(sys.platform == "win32", reason="Cannot send SIGINT on Windows.")
    def test_webagg():
        pytest.importorskip("tornado")
        proc = subprocess.Popen(
            [sys.executable, "-c",
             inspect.getsource(_test_interactive_impl)
             + "\n_test_interactive_impl()", "{}"],
            env={**os.environ, "MPLBACKEND": "webagg", "SOURCE_DATE_EPOCH": "0"})
        url = f'http://{mpl.rcParams["webagg.address"]}:{mpl.rcParams["webagg.port"]}'
        timeout = time.perf_counter() + _test_timeout
        try:
            while True:
                try:
                    retcode = proc.poll()
                    # check that the subprocess for the server is not dead
>                   assert retcode is None
E                   assert 1 is None

test-env/lib/python3.14/site-packages/matplotlib/tests/test_backends_interactive.py:493: AssertionError
----------------------------- Captured stderr call -----------------------------
Traceback (most recent call last):
  File "<string>", line 83, in <module>
    _test_interactive_impl()
    ~~~~~~~~~~~~~~~~~~~~~~^^
  File "<string>", line 69, in _test_interactive_impl
    fig.savefig(result, format='png')
    ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/figure.py", line 3490, in savefig
    self.canvas.print_figure(fname, **kwargs)
    ~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backend_bases.py", line 2186, in print_figure
    result = print_method(
        filename,
    ...<3 lines>...
        bbox_inches_restore=_bbox_inches_restore,
        **kwargs)
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backend_bases.py", line 2042, in <lambda>
    print_method = functools.wraps(meth)(lambda *args, **kwargs: meth(
                                                                 ~~~~^
        *args, **{k: v for k, v in kwargs.items() if k not in skip}))
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backends/backend_agg.py", line 481, in print_png
    self._print_pil(filename_or_obj, "png", pil_kwargs, metadata)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backends/backend_agg.py", line 429, in _print_pil
    FigureCanvasAgg.draw(self)
    ~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backends/backend_agg.py", line 382, in draw
    self.figure.draw(self.renderer)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/artist.py", line 94, in draw_wrapper
    result = draw(artist, renderer, *args, **kwargs)
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/artist.py", line 71, in draw_wrapper
    return draw(artist, renderer)
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/figure.py", line 3264, in draw
    DrawEvent("draw_event", self.canvas, renderer)._process()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backend_bases.py", line 1189, in _process
    self.canvas.callbacks.process(self.name, self)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/cbook.py", line 366, in process
    self.exception_handler(exc)
    ~~~~~~~~~~~~~~~~~~~~~~^^^^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/cbook.py", line 110, in _exception_printer
    raise exc
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/cbook.py", line 361, in process
    func(*args, **kwargs)
    ~~~~^^^^^^^^^^^^^^^^^
  File "<string>", line 65, in <lambda>
    fig.canvas.mpl_connect("draw_event", lambda event: timer.start())
                                                       ~~~~~~~~~~~^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/_api/deprecation.py", line 382, in wrapper
    return func(*inner_args, **inner_kwargs)
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backend_bases.py", line 1069, in start
    self._timer_start()
    ~~~~~~~~~~~~~~~~~^^
  File "/build/python-matplotlib/src/matplotlib/test-env/lib/python3.14/site-packages/matplotlib/backends/backend_webagg_core.py", line 139, in _timer_start
    self._task = asyncio.ensure_future(
                 ~~~~~~~~~~~~~~~~~~~~~^
        self._timer_task(max(self.interval / 1_000., 1e-6))
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/usr/lib/python3.14/asyncio/tasks.py", line 730, in ensure_future
    loop = events.get_event_loop()
  File "/usr/lib/python3.14/asyncio/events.py", line 715, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
                       % threading.current_thread().name)
RuntimeError: There is no current event loop in thread 'MainThread'.
<sys>:0: RuntimeWarning: coroutine 'TimerAsyncio._timer_task' was never awaited
=========================== short test summary info ============================
FAILED test-env/lib/python3.14/site-packages/matplotlib/tests/test_backends_interactive.py::test_webagg - assert 1 is None