fix: Event consumer should stop on input_required (#167)

Event consumer currently only stops properly for streaming events. But
for sync calls that transition to input_required state, the consumer
doesn't treat them as final events and results in queue closed
exception.

Example test:
```py
task: Task= new_task(context.message)
result = await self.agent.invoke()
message = new_agent_text_message(result)
task.status = TaskStatus(state=TaskState.input_required, message=message)
event_queue.enqueue_event(task)
```

Author: kthota-g

src/a2a/server/events/event_consumer.py

@@ -112,6 +112,7 @@ async def consume_all(self) -> AsyncGenerator[Event]:
                             TaskState.failed,
                             TaskState.rejected,
                             TaskState.unknown,
+                            TaskState.input_required
                         )
                     )
                 )

tests/server/events/test_event_consumer.py

@@ -222,3 +222,22 @@ async def mock_dequeue() -> Any:
     assert len(consumed_events) == 1
     assert consumed_events[0] == events[0]
     assert mock_event_queue.task_done.call_count == 1
+
+@pytest.mark.asyncio
+async def test_consume_task_input_required(
+    event_consumer: MagicMock,
+    mock_event_queue: MagicMock,
+):
+    task = Task(**MINIMAL_TASK)
+    task.status = TaskStatus(state=TaskState.input_required)
+
+    async def mock_dequeue() -> Any:
+        return task
+
+    mock_event_queue.dequeue_event = mock_dequeue
+    consumed_events: list[Any] = []
+    #consumer should terminate on input_required task
+    async for event in event_consumer.consume_all():
+        consumed_events.append(event)
+    assert len(consumed_events) == 1
+    assert consumed_events[0] == task