chore(deps-dev): update a2a-sdk requirement

Updates the requirements on [a2a-sdk](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](https://github.com/a2aproject/a2a-python/commits/v1.1.2)

---
updated-dependencies:
- dependency-name: a2a-sdk
  dependency-version: 1.1.2
  dependency-type: direct:development
...

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

Author: dependabot[bot]

pyproject.toml

@@ -160,7 +160,7 @@ dev = [
 ]
 
 [project.optional-dependencies]
-a2a = ["a2a-sdk[http-server]>=0.3,<0.4"]
+a2a = ["a2a-sdk[http-server]>=0.3,<1.2"]
 a2a-v1 = ["a2a-sdk[http-server]>=1.0.1,<2.0"]
 ag-ui = ["ag-ui-protocol>=0.1.10"]
 strands-agents = [