Patch: improve openai functions call parser compatibility (#15197)

```shell
Python 3.11.6 (main, Nov  2 2023, 04:39:43) [Clang 14.0.3 (clang-1403.0.22.14.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> s = {'name': 'gc', 'arguments': '{"prompt":"hi\nbob."}'}
>>> import json
>>> json.loads(s['arguments'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/homebrew/Cellar/python@3.11/3.11.6_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.6_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.6_1/Frameworks/Python.framework/Versions/3.11/lib/python3.11/json/decoder.py", line 353, in raw_decode
    obj, end = self.scan_once(s, idx)
               ^^^^^^^^^^^^^^^^^^^^^^
json.decoder.JSONDecodeError: Invalid control character at: line 1 column 14 (char 13)
>>> json.loads(s['arguments'].replace('\n', '\\n'))
{'prompt': 'hi\nbob.'}
>>>
```

---------

Co-authored-by: Nuno Campos <nuno@langchain.dev>

libs/langchain/langchain/agents/openai_functions_multi_agent/base.py

@@ -41,7 +41,7 @@ def _parse_ai_message(message: BaseMessage) -> Union[List[AgentAction], AgentFin
 
     if function_call:
         try:
-            arguments = json.loads(function_call["arguments"])
+            arguments = json.loads(function_call["arguments"], strict=False)
         except JSONDecodeError:
             raise OutputParserException(
                 f"Could not parse tool input: {function_call} because "

libs/langchain/langchain/agents/output_parsers/openai_functions.py

@@ -46,7 +46,7 @@ class OpenAIFunctionsAgentOutputParser(AgentOutputParser):
                     _tool_input = {}
                 else:
                     # otherwise it returns a json object
-                    _tool_input = json.loads(function_call["arguments"])
+                    _tool_input = json.loads(function_call["arguments"], strict=False)
             except JSONDecodeError:
                 raise OutputParserException(
                     f"Could not parse tool input: {function_call} because "