chore: Enhance a2a_agent_executor module to raise error with meaningful error message to ask user upgrade python when python version < 3.10

PiperOrigin-RevId: 776631647

src/google/adk/a2a/executor/a2a_agent_executor.py

@@ -24,6 +24,7 @@ from typing import Callable
 from typing import Optional
 import uuid
 
+try:
   from a2a.server.agent_execution import AgentExecutor
   from a2a.server.agent_execution.context import RequestContext
   from a2a.server.events.event_queue import EventQueue
@@ -33,6 +34,16 @@ from a2a.types import TaskState
   from a2a.types import TaskStatus
   from a2a.types import TaskStatusUpdateEvent
   from a2a.types import TextPart
+
+except ImportError as e:
+  import sys
+
+  if sys.version_info < (3, 10):
+    raise ImportError(
+        'A2A requires Python 3.10 or above. Please upgrade your Python version.'
+    ) from e
+  else:
+    raise e
 from google.adk.runners import Runner
 from pydantic import BaseModel
 from typing_extensions import override