input: Write a python function to normalize a dataset using the min-max normalization method.
  assert autoNorm(array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])) == (array([[0. , 0. , 0. ], [0.5, 0.5, 0.5], [1. , 1. , 1. ]]), array([6, 6, 6]), array([1, 2, 3]))
  assert autoNorm(array([[0, 0, 0], [10, 10, 10], [20, 20, 20]])) == (array([[0. , 0. , 0. ], [0.5, 0.5, 0.5], [1. , 1. , 1. ]]), array([20, 20, 20]), array([0, 0, 0]))
output: def autoNorm(dataSet):
      minVals = dataSet.min(0)
      maxVals = dataSet.max(0)
      ranges = maxVals - minVals
      normDataSet = (dataSet - minVals) / ranges
      return normDataSet, ranges, minVals