`verify_cot` fails with python 3.14

[bhearsum]

Eg:

~/repos/scriptworker ❯ uv run verify_cot --task-type signing E5t_oDq0TlezA83_NI8CmA
Traceback (most recent call last):
  File "/mnt/data/repos/scriptworker/.venv/bin/verify_cot", line 4, in <module>
    from scriptworker.cot.verify import verify_cot_cmdln
  File "/mnt/data/repos/scriptworker/src/scriptworker/cot/verify.py", line 30, in <module>
    from scriptworker.artifacts import (
    ...<5 lines>...
    )
  File "/mnt/data/repos/scriptworker/src/scriptworker/artifacts.py", line 23, in <module>
    from scriptworker.task import get_decision_task_id, get_run_id, get_task_id
  File "/mnt/data/repos/scriptworker/src/scriptworker/task.py", line 26, in <module>
    from scriptworker.github import (
    ...<5 lines>...
    )
  File "/mnt/data/repos/scriptworker/src/scriptworker/github.py", line 156, in <module>
    _fetch_github_branch_commits_data = memoize_ttl(_fetch_github_branch_commits_data_helper, get_ttl=lambda _: _BRANCH_COMMITS_CACHE_TTL_IN_SECONDS)
  File "/mnt/data/repos/scriptworker/.venv/lib/python3.14/site-packages/aiomemoizettl.py", line 6, in memoize_ttl
    loop = asyncio.get_event_loop()
  File "/home/bhearsum/.local/share/uv/python/cpython-3.14.0-linux-x86_64-gnu/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'.

[bhearsum]

This is caused by aiomemoizettl, which is unmaintained at this point. #731 is looking at replacing the need for it.