Build(deps): Bump langchain-community

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


Updates `langchain-community` from 0.3.3 to 0.3.27
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-community==0.3.3...langchain==0.3.27)

---
updated-dependencies:
- dependency-name: langchain-community
  dependency-version: 0.3.27
  dependency-type: direct:production
  dependency-group: pip
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

backend/requirements.txt

@@ -1,5 +1,5 @@
 langchain==0.3.5
-langchain-community==0.3.3
+langchain-community==0.3.27
 langchain-huggingface==0.1.1
 langchain-google-genai==2.0.3
 langchain-google-vertexai==2.0.6