fix: chat_models Qianfan not compatiable with SystemMessage (#10642)

- **Description:** QianfanEndpoint bugs for SystemMessages. When the
`SystemMessage` is input as the messages to
`chat_models.QianfanEndpoint`. A `TypeError` will be raised.
  - **Issue:** #10643
  - **Dependencies:** 
  - **Tag maintainer:** @baskaryan
  - **Twitter handle:** no

docs/extras/integrations/chat/baidu_qianfan_endpoint.ipynb

@@ -46,21 +46,26 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 5,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "[INFO] [09-15 20:00:29] logging.py:55 [t:139698882193216]: requesting llm api endpoint: /chat/eb-instant\n"
+     ]
+    }
+   ],
    "source": [
     "\"\"\"For basic init and call\"\"\"\n",
-    "from langchain.chat_models.baidu_qianfan_endpoint import QianfanChatEndpoint \n",
+    "from langchain.chat_models import QianfanChatEndpoint \n",
     "from langchain.chat_models.base import HumanMessage\n",
     "import os\n",
-    "os.environ[\"QIAFAN_AK\"] = \"xxx\"\n",
-    "os.environ[\"QIAFAN_AK\"] = \"xxx\"\n",
-    "\n",
+    "os.environ[\"QIANFAN_AK\"] = \"your_ak\"\n",
+    "os.environ[\"QIANFAN_SK\"] = \"your_sk\"\n",
     "\n",
     "chat = QianfanChatEndpoint(\n",
-    "                            qianfan_ak=\"xxx\",\n",
-    "                            qianfan_sk=\"xxx\",\n",
     "                            streaming=True, \n",
     "                            )\n",
     "res = chat([HumanMessage(content=\"write a funny joke\")])\n"
@@ -68,21 +73,55 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 6,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "[INFO] [09-15 20:00:36] logging.py:55 [t:139698882193216]: requesting llm api endpoint: /chat/eb-instant\n",
+      "[INFO] [09-15 20:00:37] logging.py:55 [t:139698882193216]: async requesting llm api endpoint: /chat/eb-instant\n"
+     ]
+    },
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "chat resp: content='您好，您似乎输入' additional_kwargs={} example=False\n",
+      "chat resp: content='了一个话题标签，请问需要我帮您找到什么资料或者帮助您解答什么问题吗？' additional_kwargs={} example=False\n",
+      "chat resp: content='' additional_kwargs={} example=False\n"
+     ]
+    },
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "[INFO] [09-15 20:00:39] logging.py:55 [t:139698882193216]: async requesting llm api endpoint: /chat/eb-instant\n"
+     ]
+    },
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "generations=[[ChatGeneration(text=\"The sea is a vast expanse of water that covers much of the Earth's surface. It is a source of travel, trade, and entertainment, and is also a place of scientific exploration and marine conservation. The sea is an important part of our world, and we should cherish and protect it.\", generation_info={'finish_reason': 'finished'}, message=AIMessage(content=\"The sea is a vast expanse of water that covers much of the Earth's surface. It is a source of travel, trade, and entertainment, and is also a place of scientific exploration and marine conservation. The sea is an important part of our world, and we should cherish and protect it.\", additional_kwargs={}, example=False))]] llm_output={} run=[RunInfo(run_id=UUID('d48160a6-5960-4c1d-8a0e-90e6b51a209b'))]\n",
+      "astream content='The sea is a vast' additional_kwargs={} example=False\n",
+      "astream content=' expanse of water, a place of mystery and adventure. It is the source of many cultures and civilizations, and a center of trade and exploration. The sea is also a source of life and beauty, with its unique marine life and diverse' additional_kwargs={} example=False\n",
+      "astream content=' coral reefs. Whether you are swimming, diving, or just watching the sea, it is a place that captivates the imagination and transforms the spirit.' additional_kwargs={} example=False\n"
+     ]
+    }
+   ],
    "source": [
     "    \n",
-    "from langchain.chat_models.baidu_qianfan_endpoint import QianfanChatEndpoint\n",
+    "from langchain.chat_models import QianfanChatEndpoint\n",
     "from langchain.schema import HumanMessage\n",
-    "import asyncio\n",
     "\n",
     "chatLLM = QianfanChatEndpoint(\n",
     "    streaming=True,\n",
     ")\n",
     "res = chatLLM.stream([HumanMessage(content=\"hi\")], streaming=True)\n",
     "for r in res:\n",
-    "    print(\"chat resp1:\", r)\n",
+    "    print(\"chat resp:\", r)\n",
     "\n",
     "\n",
     "async def run_aio_generate():\n",
@@ -113,9 +152,24 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 7,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "[INFO] [09-15 20:00:50] logging.py:55 [t:139698882193216]: requesting llm api endpoint: /chat/bloomz_7b1\n"
+     ]
+    },
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "content='你好！很高兴见到你。' additional_kwargs={} example=False\n"
+     ]
+    }
+   ],
    "source": [
     "chatBloom = QianfanChatEndpoint(\n",
     "                            streaming=True, \n",
@@ -141,9 +195,27 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 8,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "[INFO] [09-15 20:00:57] logging.py:55 [t:139698882193216]: requesting llm api endpoint: /chat/eb-instant\n"
+     ]
+    },
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "content='您好，您似乎输入' additional_kwargs={} example=False\n",
+      "content='了一个文本字符串，但并没有给出具体的问题或场景。' additional_kwargs={} example=False\n",
+      "content='如果您能提供更多信息，我可以更好地回答您的问题。' additional_kwargs={} example=False\n",
+      "content='' additional_kwargs={} example=False\n"
+     ]
+    }
+   ],
    "source": [
     "res = chat.stream([HumanMessage(content=\"hi\")], **{'top_p': 0.4, 'temperature': 0.1, 'penalty_score': 1})\n",
     "\n",
@@ -154,7 +226,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "base",
    "language": "python",
    "name": "python3"
   },
@@ -168,11 +240,11 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.2"
+   "version": "3.11.4"
   },
   "vscode": {
    "interpreter": {
-    "hash": "2d8226dd90b7dc6e8932aea372a8bf9fc71abac4be3cdd5a63a36c2a19e3700f"
+    "hash": "6fa70026b407ae751a5c9e6bd7f7d482379da8ad616f98512780b705c84ee157"
    }
   }
  },