Update custom_ops.cc (#5507)
Update custom_ops.cc (#5507)

To fix KernelInfoGetAttrbute_string get string will lose the laster char
microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime,microsoft/onnxruntime