fix: not show undefined in caption for received audio messages in group chats

Author: edisonmartinsmkt

src/api/integrations/chatbot/chatwoot/services/chatwoot.service.ts

@@ -1652,7 +1652,7 @@ export class ChatwootService {
       stickerMessage: undefined,
       documentMessage: msg.documentMessage?.caption,
       documentWithCaptionMessage: msg.documentWithCaptionMessage?.message?.documentMessage?.caption,
-      audioMessage: msg.audioMessage?.caption,
+      audioMessage: msg.audioMessage?.caption || '',
       contactMessage: msg.contactMessage?.vcard,
       contactsArrayMessage: msg.contactsArrayMessage,
       locationMessage: msg.locationMessage,