* Fix test failures on Python 3.14
As documented at
https://docs.python.org/3/library/asyncio-eventloop.html#asyncio.get_event_loop,
`get_event_loop` now fails if there is no active event loop. Since there
will never already be one at the top level of a file anyway, explicitly
create a new one every time.
* Reformat with black 2026 style
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