[ONNX] enable the onnx tests after PR #8274 merged (#9019)

* enable the onnx tests after PR #8274 merged

* fix lint

Author: Matthew Brookhart

python/tvm/relay/frontend/onnx.py

@@ -69,7 +69,11 @@ class onnx_input(list):
 
     def __getitem__(self, item):
         if isinstance(item, slice):
-            indices = list(range(item.stop)[item])
+            if item.stop is None:
+                stop = len(self)
+            else:
+                stop = item.stop
+            indices = list(range(stop)[item])
             return [self[i] for i in indices]
         if isinstance(item, int):
             return list(self)[item] if item < len(self) else None

tests/python/frontend/onnx/test_forward.py

@@ -4145,11 +4145,7 @@ def verify_nms(
     )
 
 
-# @tvm.testing.parametrize_targets
-@pytest.mark.skip(
-    "Test regressed due to not being run in CI"
-    + " tracked here: https://github.com/apache/tvm/pull/8274"
-)
+@tvm.testing.parametrize_targets
 def test_loop(target, dev):
     def verify_cond_loop():
         y_in = helper.make_tensor_value_info("y_in", TensorProto.FLOAT, [1])