FIX new test_cases on python 3.5 & 3.6

asyncio.create_task has been added in Python 3.7. The low-level asyncio.ensure_future() function can be used instead (works in all Python versions but is less readable).

https://docs.python.org/3/library/asyncio-task.html#asyncio.create_task

Author: alblasco

tests/async_fixtures/test_async_fixtures_with_finalizer.py

@@ -32,7 +32,7 @@ async def port_afinalizer():
             await finalizer
         event_loop.run_until_complete(port_afinalizer())
 
-    worker = asyncio.create_task(asyncio.sleep(0.2))
+    worker = asyncio.ensure_future(asyncio.sleep(0.2))
     request.addfinalizer(functools.partial(port_finalizer, worker))
     return True
 
@@ -46,6 +46,6 @@ async def port_afinalizer():
             await finalizer
         asyncio.get_event_loop().run_until_complete(port_afinalizer())
 
-    worker = asyncio.create_task(asyncio.sleep(0.2))
+    worker = asyncio.ensure_future(asyncio.sleep(0.2))
     request.addfinalizer(functools.partial(port_finalizer, worker))
     return True