fix: convert auth_required state in proto utils (#444)

# Description

The A2A client is receiving `unknown` state over REST transport while it
should receive `auth_required`.

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---------

Signed-off-by: Tomas Pilar <thomas7pilar@gmail.com>

Author: pilartomas

src/a2a/utils/proto_utils.py

@@ -122,6 +122,8 @@ def task_state(cls, state: types.TaskState) -> a2a_pb2.TaskState:
                 return a2a_pb2.TaskState.TASK_STATE_FAILED
             case types.TaskState.input_required:
                 return a2a_pb2.TaskState.TASK_STATE_INPUT_REQUIRED
+            case types.TaskState.auth_required:
+                return a2a_pb2.TaskState.TASK_STATE_AUTH_REQUIRED
             case _:
                 return a2a_pb2.TaskState.TASK_STATE_UNSPECIFIED
 
@@ -568,6 +570,8 @@ def task_state(cls, state: a2a_pb2.TaskState) -> types.TaskState:
                 return types.TaskState.failed
             case a2a_pb2.TaskState.TASK_STATE_INPUT_REQUIRED:
                 return types.TaskState.input_required
+            case a2a_pb2.TaskState.TASK_STATE_AUTH_REQUIRED:
+                return types.TaskState.auth_required
             case _:
                 return types.TaskState.unknown
 

tests/utils/test_proto_utils.py

@@ -170,11 +170,7 @@ def test_enum_conversions(self):
         )
 
         for state in types.TaskState:
-            if state not in (
-                types.TaskState.unknown,
-                types.TaskState.rejected,
-                types.TaskState.auth_required,
-            ):
+            if state not in (types.TaskState.unknown, types.TaskState.rejected):
                 proto_state = proto_utils.ToProto.task_state(state)
                 assert proto_utils.FromProto.task_state(proto_state) == state