chore: bump @modelcontextprotocol/sdk in the dependencies group

Bumps the dependencies group with 1 update: [@modelcontextprotocol/sdk](https://github.com/modelcontextprotocol/typescript-sdk).


Updates `@modelcontextprotocol/sdk` from 1.20.2 to 1.21.1
- [Release notes](https://github.com/modelcontextprotocol/typescript-sdk/releases)
- [Commits](modelcontextprotocol/typescript-sdk@1.20.2...1.21.1)

---
updated-dependencies:
- dependency-name: "@modelcontextprotocol/sdk"
  dependency-version: 1.21.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
  dependency-group: dependencies
...

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

Author: dependabot[bot]