[Test] Fix dummy http server on python 3.6

test/functional/util/dummy_http.py

@@ -141,4 +141,5 @@ async def main():
     await asyncio.Event().wait()
 
 if __name__ == "__main__":
-    asyncio.run(main())
+    loop = asyncio.get_event_loop()
+    loop.run_until_complete(main())