chore(deps): update a2a-sdk[http-server] requirement in /python

Updates the requirements on [a2a-sdk[http-server]](https://github.com/a2aproject/a2a-python) to permit the latest version.
- [Release notes](https://github.com/a2aproject/a2a-python/releases)
- [Changelog](https://github.com/a2aproject/a2a-python/blob/main/CHANGELOG.md)
- [Commits](a2aproject/a2a-python@v0.3.23...v1.0.3)

---
updated-dependencies:
- dependency-name: a2a-sdk[http-server]
  dependency-version: 1.0.2
  dependency-type: direct:production
...

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Author: dependabot[bot]