Bump torch from 2.1.0 to 2.8.0 in /financial/vector-mcp-ai-agents

Bumps [torch](https://github.com/pytorch/pytorch) from 2.1.0 to 2.8.0.
- [Release notes](https://github.com/pytorch/pytorch/releases)
- [Changelog](https://github.com/pytorch/pytorch/blob/main/RELEASE.md)
- [Commits](pytorch/pytorch@v2.1.0...v2.8.0)

---
updated-dependencies:
- dependency-name: torch
  dependency-version: 2.8.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

financial/vector-mcp-ai-agents/requirements_backend.txt

@@ -18,7 +18,7 @@ numpy>=1.26.0
 pandas>=2.2.0
 
 # Optional AI/ML dependencies
-torch==2.1.0
+torch==2.8.0
 transformers==4.36.0
 openai==1.3.8