fix issue with ms-domain test

Author: guschmue

tests/test_backend.py

@@ -3190,7 +3190,6 @@ def func(X, K):
                 k_val = np.array(raw_k).astype(np.int32)
                 self._run_test_case(func, [_OUTPUT, _OUTPUT1], {_INPUT: x_val, _INPUT1: k_val})
 
-    @check_opset_min_version(12)
     @test_ms_domain()
     def test_inverse(self):
         # this depends on onnx Inverse which was removed from opset-12 but does exists in the ms-domain

tools/dump-onnx.py

@@ -14,6 +14,7 @@
 import collections
 import re
 
+import onnx
 from onnx import ModelProto
 from onnx import helper, shape_inference