Fix MaxListenersExceededWarning with new ConversationStore

[ZeroTricks]

After a conversation with ~20 turns in CLI:

ERROR: (node:1473736) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 close listeners added to [Interface]. MaxListeners is 10. Use emitter.setMaxListeners() to increase limit (Use `node --trace-warnings ...` to show where the warning was created)