Fix failing test for serialization (#21344)

Thank you for contributing to LangChain!

- [ ] **PR title**: "package: description"
- Where "package" is whichever of langchain, community, core,
experimental, etc. is being modified. Use "docs: ..." for purely docs
changes, "templates: ..." for template changes, "infra: ..." for CI
changes.
  - Example: "community: add foobar LLM"


- [ ] **PR message**: ***Delete this entire checklist*** and replace
with
    - **Description:** a description of the change
    - **Issue:** the issue # it fixes, if applicable
    - **Dependencies:** any dependencies required for this change
- **Twitter handle:** if your PR gets announced, and you'd like a
mention, we'll gladly shout you out!


- [ ] **Add tests and docs**: If you're adding a new integration, please
include
1. a test for the integration, preferably unit tests that do not rely on
network access,
2. an example notebook showing its use. It lives in
`docs/docs/integrations` directory.


- [ ] **Lint and test**: Run `make format`, `make lint` and `make test`
from the root of the package(s) you've modified. See contribution
guidelines for more: https://python.langchain.com/docs/contributing/

Additional guidelines:
- Make sure optional dependencies are imported within a function.
- Please do not add dependencies to pyproject.toml files (even optional
ones) unless they are required for unit tests.
- Most PRs should not touch more than one package.
- Changes should be backwards compatible.
- If you are adding something to community, do not re-import it in
langchain.

If no one reviews your PR within a few days, please @-mention one of
baskaryan, efriis, eyurtsev, hwchase17.

libs/langchain/tests/unit_tests/load/test_load.py

@@ -141,13 +141,16 @@ def test_load_llmchain_env() -> None:
         del os.environ["OPENAI_API_KEY"]
 
 
-@pytest.mark.requires("openai")
+@pytest.mark.requires("openai", "langchain_openai")
 def test_load_llmchain_with_non_serializable_arg() -> None:
-    llm = CommunityOpenAI(  # type: ignore[call-arg]
+    import httpx
+    from langchain_openai import OpenAI
+
+    llm = OpenAI(  # type: ignore[call-arg]
         model="davinci",
         temperature=0.5,
         openai_api_key="hello",
-        http_client=NotSerializable,
+        http_client=httpx.Client(),
     )
     prompt = PromptTemplate.from_template("hello {name}!")
     chain = LLMChain(llm=llm, prompt=prompt)