Update website example to Python 3

[dancojocaru2000]

Python 2 is discontinued, no longer receiving updates, and to be avoided unless absolutely necessary. Not even security fixes will be provided.

Considering this, the example on the website should be updated to Python 3:

# how to ace an interview
for i in range(1, 101):
    if i % 15 == 0:
        print("mononoki")
    elif i % 3 == 0:
        print("mono")
    elif i % 5 == 0:
        print("noki")
    else:
        print(i)