fix(test_asyncioreactor.py): handle AttribueError from asynctest

asyncio connection backend is mostly broken, and need refactoring
for now we'll just skip the test on error from importing asynctest
which is broken for python 3.11

Author: fruch

tests/unit/io/test_asyncioreactor.py

@@ -3,7 +3,7 @@
     from cassandra.io.asyncioreactor import AsyncioConnection
     import asynctest
     ASYNCIO_AVAILABLE = True
-except (ImportError, SyntaxError):
+except (ImportError, SyntaxError, AttributeError):
     AsyncioConnection = None
     ASYNCIO_AVAILABLE = False