fix(mge/subgraph): fix mem leak

GitOrigin-RevId: dc7bfe6265a5ac7e7d9c02d29d7ca3084ddcabf8

imperative/python/src/ops.cpp

@@ -450,6 +450,7 @@ void _init_py_op_def(py::module m) {
     py_type.tp_richcompare = PyOp(OpDef)::tp_richcompare;
     py_type.tp_getset = py_op::py_getsetters;
     py_type.tp_repr = py_op::py_repr;
+    py_type.tp_dealloc = py_dealloc_generic<PyOp(OpDef)>;
     mgb_assert(PyType_Ready(&py_type) >= 0);
     m.add_object("OpDef", reinterpret_cast<PyObject*>(&py_type));
 }