chore(deps): update langchain-openai requirement

Updates the requirements on [langchain-openai](https://github.com/langchain-ai/langchain) to permit the latest version.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-openai==1.0.0...langchain-openai==1.6.1)

---
updated-dependencies:
- dependency-name: langchain-openai
  dependency-version: 1.6.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

examples/nams-langchain/requirements.txt

@@ -5,6 +5,6 @@ langchain>=1.0,<2
 langchain-core>=1.0,<2
 # Only needed for a real model turn; the script falls back to a scripted
 # offline chat model when OPENAI_API_KEY is unset.
-langchain-openai>=1.0,<2
+langchain-openai>=1.6.1,<2
 # Optional: loads this directory's .env.
 python-dotenv>=1.0,<2