input: Write a python function to sort a list in descending order using bubble sort.
  assert bubbleSort([54,26,93,17,77,31,44,55,20]) == [93, 77, 55, 54, 44, 31, 26, 20, 17]
  assert bubbleSort([1, 2, 3, 4, 5]) == [5, 4, 3, 2, 1]
  assert bubbleSort([10, 9, 8, 7, 6, 5, 4, 3, 2, 1]) == [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
output: def bubbleSort(arr):
      n = len(arr)
      for i in range(n):
          for j in range(0, n-i-1):
              if arr[j] < arr[j+1]:
                  arr[j], arr[j+1] = arr[j+1], arr[j]
      return arr