how to get 3 unique values using random.randint() in python?

I am trying to populate a list in Python3 with 3 random items being read from a file using REGEX, however i keep getting duplicate items in the list. Here is an example.

import re
import random as rn

data = '/root/Desktop/Selenium[FILTERED].log'
with open(data, 'r') as inFile:
    index = inFile.read()
    URLS = re.findall(r'https://www\.arbitrarywebsite\.com/view\?i=\w{1,20}', index)

    list_0 = []
    for i in range(3):
        list_0.append(URLS[rn.randint(1, 30)])
    inFile.close()

for i in range(len(list_0)):
    print(list_0[i])

What would be the cleanest way to prevent duplicate items being appended to the list?