Add scenario for pytest.raises() with pytest.fail() in context manager

[jamescooke]

As per Pytest deprecations documentation, message= is deprecated. That all seems fine 👍🏻

However, the suggested solution packs a pytest.fail() into the context manager:

with pytest.raises(TimeoutError):
    wait_for(websocket.recv(), 0.5)
    pytest.fail("Client got unexpected message")

At the very least this needs a new "good" example to be added to ensure that it works with AAA.

However, my guess is that we might need some fixes / adjustment for default or greedy act blocks.