server: Explicitly create asyncio event loop for python 3.14

[jonrebm]

Starting with python 3.14, asyncio.get_event_loop() "Raises a RuntimeError if there is no current event loop." which we hit when trying to run the server with 3.14.3:

  File "flamingo/test-site/env/bin/flamingo", line 27, in <module>
    runpy.run_path(scripts[args.command])
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen runpy>", line 287, in run_path
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "flamingo/test-site/env/bin/_flamingo-server", line 63, in <module>
    loop = asyncio.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'.

Create the event loop instead.

[jonrebm]

CI failure seems to not be my fault we have
flamingo/plugins/rst/bootstrap3.py:75:80: E501 line too long (124 > 79 characters)
and
Error: The version '3.7' with architecture 'x64' was not found for Ubuntu 24.04.

[SmithChart]

CI failure seems to not be my fault we have flamingo/plugins/rst/bootstrap3.py:75:80: E501 line too long (124 > 79 characters) and Error: The version '3.7' with architecture 'x64' was not found for Ubuntu 24.04.

Yes. Fixing that is part of a larger changeset I am currently preparing. Sorry for that noise!

[SmithChart]

Thanks for the fix. I've given this a test on Python 3.11 (Debian oldstable) and python 3.13 (Debian stable) and it works there, too.

So: Looks good to me.