Fix Uvicorn/Asyncio untime error in worker.py

[GrantDeljevic]

Below error occurred, the ignore_signals() handler in worker.py ran into an error caused by a recent uvicorn update when it tries to call asyncio.get_event_loop() where none exists.

Traceback (most recent call last):
  File "/python3.10/multiprocessing/process.py", line 314, in _bootstrap
    self.run()
  File "/python3.10/site-packages/mlserver/parallel/worker.py", line 70, in run
    self._ignore_signals()
  File "/python3.10/site-packages/mlserver/parallel/worker.py", line 81, in _ignore_signals
    loop = asyncio.get_event_loop()
  File "/python3.10/site-packages/uvloop/__init__.py", line 206, in get_event_loop
    raise RuntimeError(
RuntimeError: There is no current event loop in thread 'MainThread'.

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[GrantDeljevic]

PR was created twice, closing for duplicate