Fix failing test

Author: oremanj

trio_asyncio/_loop.py

@@ -417,7 +417,10 @@ async def async_main(*args):
 
                     @sync_nursery.start_soon
                     async def wait_for_sync():
-                        await loop.synchronize()
+                        try:
+                            await loop.synchronize()
+                        except RuntimeError:  # "Event loop is closed"
+                            pass
                         sync_nursery.cancel_scope.cancel()
 
                     await loop.wait_stopped()