fix validate

Author: xadupre

onnx_diagnostic/torch_models/validate.py

@@ -830,7 +830,7 @@ def node_iter(proto):
                 yield node
                 for att in node.attribute:
                     if att.type == onnx.AttributeProto.GRAPH:
-                        yield from att.g
+                        yield from node_iter(att.g)
             if hasattr(proto, "initializer"):
                 yield from proto.initializer
         else: