[ShapeInf] correct ReLU op_type typo in MultiThreshold shape inf

src/finn/transformation/infer_shapes.py

 import onnx.helper as helper
 import onnx.shape_inference as si
 
-import finn.core.onnx_exec as oxe
 from finn.core.modelwrapper import ModelWrapper
 
+
 def _make_shape_compatible_op(node):
     """Return a shape-compatible non-FINN op for a given FINN op. Used for
     shape inference with custom ops."""
-    assert(node.domain == "finn")
+    assert node.domain == "finn"
     if node.op_type == "MultiThreshold":
-        return helper.make_node("ReLU", [node.input[0]], [node.output[0]])
+        return helper.make_node("Relu", [node.input[0]], [node.output[0]])
     else:
         raise Exception("No known shape-compatible op for %s" % node.op_type)
 
+
 def _hide_finn_ops(model):
     """Replace any FINN ops by shape-compatible ones, and return a dict that
     can be used to map the string representations of the new (shape-compatible)
@@ -28,6 +29,7 @@ def _hide_finn_ops(model):
             model.graph.node.remove(node)
     return hidden_ops
 
+
 def _restore_finn_ops(model, hidden_ops):
     """Replace any shape-compatible ops with the FINN ops that originally
     generated them."""