Make qualification work with pytest-dev/pytest-asyncio#871

This should not be merged until that PR is released and we switch to that
version (probably 0.24).

qualification/conftest.py

@@ -28,6 +28,7 @@
 
 import matplotlib.style
 import pytest
+import pytest_asyncio
 import pytest_check
 from katsdpservices import get_interface_address
 
@@ -176,14 +177,10 @@ def key(item: pytest.Item) -> tuple:
         return tuple(ans)
 
     items.sort(key=key)
-
-
-# Need to redefine this from pytest-asyncio to have it at session scope
-@pytest.fixture(scope="session")
-def event_loop():  # noqa: D103
-    loop = asyncio.get_event_loop_policy().new_event_loop()
-    yield loop
-    loop.close()
+    scope_marker = pytest.mark.asyncio(loop_scope="session")
+    for item in items:
+        if pytest_asyncio.is_async_test(item):
+            item.add_marker(scope_marker, append=False)
 
 
 @pytest.fixture(scope="package")