DeprecationWarning when running the tests on py3.9

[DavidBord]

python -W default -m unittest ................................./Users/db/venvs/websockets39/lib/python3.9/site-packages/websockets-8.1-py3.9-macosx-10.15-x86_64.egg/websockets/server.py:716: DeprecationWarning: The explicit passing of coroutine objects to asyncio.wait() is deprecated since Python 3.8, and scheduled for removal in Python 3.11. await asyncio.wait( ../Users/db/venvs/websockets39/lib/python3.9/site-packages/websockets-8.1-py3.9-macosx-10.15-x86_64.egg/websockets/server.py:716: DeprecationWarning: The explicit passing of coroutine objects to asyncio.wait() is deprecated since Python 3.8, and scheduled for removal in Python 3.11. await asyncio.wait( ...../Users/db/venvs/websockets39/lib/python3.9/site-packages/websockets-8.1-py3.9-macosx-10.15-x86_64.egg/websockets/server.py:716: DeprecationWarning: The explicit passing of coroutine objects to asyncio.wait() is deprecated since Python 3.8, and scheduled for removal in Python 3.11. await asyncio.wait( ........................................../Users/db/venvs/websockets39/lib/python3.9/site-packages/websockets-8.1-py3.9-macosx-10.15-x86_64.egg/websockets/server.py:716: DeprecationWarning: The explicit passing of coroutine objects to asyncio.wait() is deprecated since Python 3.8, and scheduled for removal in Python 3.11. await asyncio.wait( ./Users/db/venvs/websockets39/lib/python3.9/site-packages/websockets-8.1-py3.9-macosx-10.15-x86_64.egg/websockets/server.py:716: DeprecationWarning: The explicit passing of coroutine objects to asyncio.wait() is deprecated since Python 3.8, and scheduled for removal in Python 3.11. await asyncio.wait( .....