Contruct a python program that sorts an array of strings using BubbleSort algorithm.
["Hello", "World", "Boo", "Yay"]
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