Write a Python script that sorts an array of strings in alphabetical order case insensitively.
["Apple", "Banana", "orange"]
def sort_array(arr): 
    arr.sort(key = lambda x: x.lower()) 
    return arr

# driver code 
arr = ["Apple", "Banana", "orange"] 
print(sort_array(arr)) 
# Output: ['Apple', 'Banana', 'orange']