fix: set accepted user agent for APInex STT

bot.py

@@ -52,6 +52,7 @@ async def transcribe_audio(audio: bytes, content_type: str, api_key: str) -> str
         "Authorization": f"Bearer {api_key}",
         "Content-Type": content_type,
         "Accept": "application/json",
+        "User-Agent": "Mozilla/5.0 (compatible; SocialPostWriterBot/1.0)",
     }
     async with aiohttp.ClientSession(timeout=timeout) as session:
         async with session.post(APINEX_STT_URL, data=audio, headers=headers) as response: