We are redefining the event_loop fixture of pytest-asyncio in a deprecated way

[chrisguidry]

This warning has started to show up from pytest-asyncio and we are currently suppressing it:

E               DeprecationWarning: The event_loop fixture provided by pytest-asyncio has been redefined in
E               /home/runner/work/prefect/prefect/tests/conftest.py:211
E               Replacing the event_loop fixture with a custom implementation is deprecated
E               and will lead to errors in the future.
E               If you want to request an asyncio event loop with a scope other than function
E               scope, use the "scope" argument to the asyncio mark when marking the tests.
E               If you want to return different types of event loops, use the event_loop_policy
E               fixture.