core[patch]: set version="v2" as default in astream_events (#29894)

libs/core/tests/unit_tests/runnables/test_runnable_events_v2.py

@@ -1,6 +1,7 @@
 """Module that contains tests for runnable.astream_events API."""
 
 import asyncio
+import inspect
 import sys
 import uuid
 from collections.abc import AsyncIterator, Iterable, Iterator, Sequence
@@ -2793,3 +2794,10 @@ async def test_custom_event_root_dispatch_with_in_tool() -> None:
             },
         ],
     )
+
+
+def test_default_is_v2() -> None:
+    """Test that we default to version="v2"."""
+
+    signature = inspect.signature(Runnable.astream_events)
+    assert signature.parameters["version"].default == "v2"