Update README.md

Author: vinoo999

README.md

@@ -48,7 +48,6 @@ Install the core SDK and any desired extras using your preferred package manager
 | ------------------------ | ------------------------------------------ | -------------------------------------------- |
 | **Core SDK**             | `uv add a2a-sdk`                           | `pip install a2a-sdk`                        |
 | **All Extras**           | `uv add "a2a-sdk[all]"`                    | `pip install "a2a-sdk[all]"`                 |
-| **protobuf**             | `uv add "a2a-sdk[proto]"`                  | `pip install "a2a-sdk[proto]"`               |
 | **JSON-RPC Server**      | `uv add "a2a-sdk[jsonrpc-server]"`         | `pip install "a2a-sdk[jsonrpc-server]"`         |
 | **HTTP (REST) Server**   | `uv add "a2a-sdk[http-server]"`            | `pip install "a2a-sdk[http-server]"`         |
 | **gRPC Support**         | `uv add "a2a-sdk[grpc]"`                   | `pip install "a2a-sdk[grpc]"`                |