Bump the pip group across 1 directory with 3 updates

Bumps the pip group with 3 updates in the /backend directory: [langchain-community](https://github.com/langchain-ai/langchain), [python-multipart](https://github.com/Kludex/python-multipart) and [requests](https://github.com/psf/requests).


Updates `langchain-community` from 0.2.17 to 0.3.27
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-community==0.2.17...langchain==0.3.27)

Updates `python-multipart` from 0.0.6 to 0.0.18
- [Release notes](https://github.com/Kludex/python-multipart/releases)
- [Changelog](https://github.com/Kludex/python-multipart/blob/master/CHANGELOG.md)
- [Commits](Kludex/python-multipart@0.0.6...0.0.18)

Updates `requests` from 2.31.0 to 2.32.4
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/main/HISTORY.md)
- [Commits](psf/requests@v2.31.0...v2.32.4)

---
updated-dependencies:
- dependency-name: langchain-community
  dependency-version: 0.3.27
  dependency-type: direct:production
  dependency-group: pip
- dependency-name: python-multipart
  dependency-version: 0.0.18
  dependency-type: direct:production
  dependency-group: pip
- dependency-name: requests
  dependency-version: 2.32.4
  dependency-type: direct:production
  dependency-group: pip
...

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

Author: dependabot[bot]

backend/requirements.txt

@@ -2,13 +2,13 @@ fastapi==0.104.1
 uvicorn[standard]==0.24.0
 langchain==0.2.16
 langchain-openai==0.1.25
-langchain-community==0.2.17
+langchain-community==0.3.27
 chromadb==0.4.24
 python-dotenv==1.0.0
 pydantic==2.11.7
 pandas==2.1.4
 numpy==1.26.2
-python-multipart==0.0.6
-requests==2.31.0
+python-multipart==0.0.18
+requests==2.32.4
 aiofiles==24.1.0
 supabase==2.18.1