chore(deps): bump langchain-openai (#16)

Bumps the pip group with 1 update in the /backend directory: [langchain-openai](https://github.com/langchain-ai/langchain).


Updates `langchain-openai` from 0.3.12 to 1.1.14
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-openai==0.3.12...langchain-openai==1.1.14)

---
updated-dependencies:
- dependency-name: langchain-openai
  dependency-version: 1.1.14
  dependency-type: direct:production
  dependency-group: pip
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

backend/requirements.txt

@@ -10,7 +10,7 @@ bcrypt==4.0.1
 python-multipart==0.0.26
 psycopg2-binary==2.9.11
 langchain==0.3.23
-langchain-openai==0.3.12
+langchain-openai==1.1.14
 langchain_core==1.2.28
 langgraph>=0.2.0
 langfuse==2.60.2