Handle mp3 attachments as audio messages

Extended the condition for the audio message handling in the chatbot to recognize MP3 audio files sent as file attachments. This ensures that MP3 files will be properly processed as audio messages, improving the bot's media handling capabilities. This is just a test at this point, and may be rolled back.

src/gptbot/classes/bot.py

@@ -1146,7 +1146,7 @@ class GPTBot:
                     message_body = message.body if not self.chat_api.supports_chat_images() else [{"type": "text", "text": message.body}]
                     chat_messages.append({"role": role, "content": message_body})
 
-            if isinstance(message, RoomMessageAudio):
+            if isinstance(message, RoomMessageAudio) or (isinstance(message, RoomMessageFile) and message.body.endswith(".mp3")):
                 role = (
                     "assistant" if message.sender == self.matrix_client.user_id else "user"
                 )