groq[patch]: groq proxy support (#20758)

# Proxy Fix for Groq Class 🐛 🚀

## Description
This PR fixes a bug related to proxy settings in the `Groq` class,
allowing users to connect to LangChain services via a proxy.

## Changes Made
- ✅ FIX support for specifying proxy settings in the `Groq` class.
- ✅ Resolved the bug causing issues with proxy settings.
- ❌ Did not include unit tests and documentation updates.
- ❌ Did not run make format, make lint, and make test to ensure code
quality and functionality because I couldn't get it to run, so I don't
program in Python and couldn't run `ruff`.
- ❔ Ensured that the changes are backwards compatible.
- ✅ No additional dependencies were added to `pyproject.toml`.

### Error Before Fix
```python
Traceback (most recent call last):
  File "/home/bg/Documents/code/github.com/back2nix/test/groq/main.py", line 9, in <module>
    chat = ChatGroq(
           ^^^^^^^^^
  File "/home/bg/Documents/code/github.com/back2nix/test/groq/venv310/lib/python3.11/site-packages/langchain_core/load/serializable.py", line 120, in __init__
    super().__init__(**kwargs)
  File "/home/bg/Documents/code/github.com/back2nix/test/groq/venv310/lib/python3.11/site-packages/pydantic/v1/main.py", line 341, in __init__
    raise validation_error
pydantic.v1.error_wrappers.ValidationError: 1 validation error for ChatGroq
__root__
  Invalid `http_client` argument; Expected an instance of `httpx.AsyncClient` but got <class 'httpx.Client'> (type=type_error)
  ```
  
### Example usage after fix
  ```python3
import os

import httpx
from langchain_core.prompts import ChatPromptTemplate
from langchain_groq import ChatGroq

chat = ChatGroq(
    temperature=0,
    groq_api_key=os.environ.get("GROQ_API_KEY"),
    model_name="mixtral-8x7b-32768",
    http_client=httpx.Client(
        proxies="socks5://127.0.0.1:1080",
        transport=httpx.HTTPTransport(local_address="0.0.0.0"),
    ),
    http_async_client=httpx.AsyncClient(
        proxies="socks5://127.0.0.1:1080",
        transport=httpx.HTTPTransport(local_address="0.0.0.0"),
    ),
)

system = "You are a helpful assistant."
human = "{text}"
prompt = ChatPromptTemplate.from_messages([("system", system), ("human", human)])

chain = prompt | chat
out = chain.invoke({"text": "Explain the importance of low latency LLMs"})

print(out)
```

---------

Co-authored-by: Bagatur <22008038+baskaryan@users.noreply.github.com>
Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/partners/groq/langchain_groq/chat_models.py

@@ -126,6 +126,9 @@ class ChatGroq(BaseChatModel):
     # [httpx documentation](https://www.python-httpx.org/api/#client) for more details.
     http_client: Union[Any, None] = None
     """Optional httpx.Client."""
+    http_async_client: Union[Any, None] = None
+    """Optional httpx.AsyncClient. Only used for async invocations. Must specify
+        http_client as well if you'd like a custom client for sync invocations."""
 
     class Config:
         """Configuration for this pydantic object."""
@@ -182,17 +185,20 @@ class ChatGroq(BaseChatModel):
             "max_retries": values["max_retries"],
             "default_headers": values["default_headers"],
             "default_query": values["default_query"],
-            "http_client": values["http_client"],
         }
 
         try:
             import groq
 
+            sync_specific = {"http_client": values["http_client"]}
             if not values.get("client"):
-                values["client"] = groq.Groq(**client_params).chat.completions
+                values["client"] = groq.Groq(
+                    **client_params, **sync_specific
+                ).chat.completions
             if not values.get("async_client"):
+                async_specific = {"http_client": values["http_async_client"]}
                 values["async_client"] = groq.AsyncGroq(
-                    **client_params
+                    **client_params, **async_specific
                 ).chat.completions
         except ImportError:
             raise ImportError(