chore(deps): update mcp requirement in /mcp-server

Updates the requirements on [mcp](https://github.com/modelcontextprotocol/python-sdk) to permit the latest version.
- [Release notes](https://github.com/modelcontextprotocol/python-sdk/releases)
- [Changelog](https://github.com/modelcontextprotocol/python-sdk/blob/main/RELEASE.md)
- [Commits](modelcontextprotocol/python-sdk@v1.2.0...v2.3.0)

---
updated-dependencies:
- dependency-name: mcp
  dependency-version: 2.3.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

mcp-server/requirements.txt

@@ -1 +1 @@
-mcp>=1.2.0,<2
+mcp>=2.3.0,<3