feat: add debug log for invalid response

ref #28

src/gemini_webapi/client.py

@@ -356,8 +356,9 @@ async def generate_content(
  raise Exception
  except Exception:
  await self.close()
+ logger.debug(f"Invalid response: {response.text}")
  raise APIError(
- f"Failed to generate contents. Invalid response data received: {response.text}. Client will try to re-initialize on next request."
+ "Failed to generate contents. Invalid response data received. Client will try to re-initialize on next request."
  )
 
  try: