Build(deps): Bump langchain-openai in /.config/python/dev

Bumps [langchain-openai](https://github.com/langchain-ai/langchain) from 1.5.2 to 1.6.0.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-openai==1.5.2...langchain-openai==1.6.0)

---
updated-dependencies:
- dependency-name: langchain-openai
  dependency-version: 1.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

.config/python/dev/requirements.txt

@@ -34,7 +34,7 @@ langchain_anthropic==1.5.6
 langchain_deepseek==1.1.0
 langchain_google_genai==4.3.5
 langchain_mistralai==1.1.6
-langchain_openai==1.5.2
+langchain_openai==1.6.0
 langchain_community==0.4.2
 langsmith==0.11.1
 orjson==3.12.0