A2A specification upgrade

[hyprh]

Hi, A2A protocol had a major incompatible upgrade recently. Does the project plan to adopt this upgrade?

Previous Specification: A2A v0.1.0 JSON Schema
Current Specification: A2A v0.2.0 JSON Schema

And the trpc-a2a-go framework has completed adaptation to the new A2A specification.
Related changelog : https://github.com/trpc-group/trpc-a2a-go/blob/main/CHANGELOG.md