Upgrade third_party/python_runtime/v3_13_unstable to 3.13.11
Replaced custom PriorityStr with standard tuple sorting in _graph_node_flatten. Python 3.13 optimized str comparison bypasses custom subclasses (causing TypeError), and used getattr in _setattr because unflattening order becomes non-deterministic (preventing AttributeError).
PiperOrigin-RevId: 886082903
