Update pytest-asyncio (#2511)

requirements.txt

@@ -31,7 +31,7 @@ isort==5.10.1
 mypy==0.982
 types-certifi==2021.10.8.2
 pytest==7.2.0
-pytest-asyncio==0.19.0
+pytest-asyncio==0.20.3
 pytest-trio==0.7.0
 trio==0.21.0
 trio-typing==0.7.0