Fix tests for Python 3.14

[martincostello]

Update asyncio event loop so it works on Python 3.14.

Fixes #581.

Depends on #580 to rebase.

[w3cbot]

martincostello marked as non substantive for IPR from ash-nazg.

[dyladan]

I think this can be reviewed and merged separately from the other PR. You can just remove the changes you made to the self_test.yml and bump the version to latest.

[martincostello]

I felt the approach of merging #581 then this one doesn't mean I fix my issue (3.14 not working) but causes an issue for someone else by accident.

[maraisr]

Ah thanks for this! Can't wait for this land. In tctx I had to wrap the harness in this:

https://github.com/maraisr/tctx/blob/b921308d1f2fa089f4b21714f36fd395e18360dc/validation/test.sh#L19-L24

import asyncio, runpy, sys

sys.path.insert(0, "w3c/test")
sys.argv = ["w3c/test/test.py", *sys.argv[1:]]
asyncio.set_event_loop(asyncio.new_event_loop())
runpy.run_path("w3c/test/test.py", run_name="__main__")

[zacharycmontoya]

LGTM