[EventHub] run update python snippet (Azure#38463)

Author: swathipil

sdk/eventhub/azure-eventhub/README.md

@@ -149,7 +149,7 @@ def send_event_data_batch(producer):
     # Without specifying partition_id or partition_key
     # the events will be distributed to available partitions via round-robin.
     event_data_batch = producer.create_batch()
-    event_data_batch.add(EventData('Single message'))
+    event_data_batch.add(EventData("Single message"))
     producer.send_batch(event_data_batch)
 ```