asyncio: fix ag_frame/cr_frame typo in call graph

Fix a typo in asyncio call graph introspection.
When handling objects with `ag_await`, the code incorrectly accesses
`cr_frame`. Async generators expose their frame via `ag_frame`.
This path seems effectively unreachable in normal asyncio execution;
the change only corrects an attribute typo.

Signed-off-by: Yongtao Huang <yongtaoh2022@gmail.com>

Author: hyongtao-code

Lib/asyncio/graph.py

@@ -62,7 +62,7 @@ def _build_graph_for_future(
             coro = coro.cr_await
         elif hasattr(coro, 'ag_await'):
             # A native async generator or duck-type compatible iterator
-            st.append(FrameCallGraphEntry(coro.cr_frame))
+            st.append(FrameCallGraphEntry(coro.ag_frame))
             coro = coro.ag_await
         else:
             break