My Python program has syntax errors on newer Python versions

Question

I've been working on this Python program for a few weeks and have finally got it working... on Ubuntu Bionic. They must have an older Python version because on Reborn OS which is Arch Linux the program will not run. It gets syntax errors. The one on Ubuntu is 2.7.15 and the one on Reborn OS is 3.6.6. I get the following error:

[caden@Reborn ~]$ python ~/Dropbox/kodebyter/kodebyter.py 
  File "/home/caden/Dropbox/kodebyter/kodebyter.py", line 34
    print str(rotation)
            ^
SyntaxError: invalid syntax

My script is like this:

import string
import collections


def caesar(rotate_string, number_to_rotate_by):

    upper = collections.deque(string.ascii_uppercase)
    lower = collections.deque(string.ascii_lowercase)

    upper.rotate(number_to_rotate_by)
    lower.rotate(number_to_rotate_by)

    upper = ''.join(list(upper))
    lower = ''.join(list(lower))

    return rotate_string.translate(string.maketrans(string.ascii_uppercase, upper)).translate(string.maketrans(string.ascii_lowercase, lower))

print("Welcome to Kode Byter!")

print("Press Ctrl+C at any time to exit")

print("Press Ctrl+Shift+C to copy")

print("Press Ctrl+Shift+V to paste")

print("Will exit in 5")

print("Enter message:")
message = raw_input()

print("Enter rotation:")
rotation = raw_input()

print str(rotation)
print caesar(message, int(rotation))

print("Will exit in 4")

print("Enter message:")
message = raw_input()

print("Enter rotation:")
rotation = raw_input()

print str(rotation)
print caesar(message, int(rotation))

print("Will exit in 3")

print("Enter message:")
message = raw_input()

print("Enter rotation:")
rotation = raw_input()

print str(rotation)
print caesar(message, int(rotation))

print("Will exit in 2")

print("Enter message:")
message = raw_input()

print("Enter rotation:")
rotation = raw_input()

print str(rotation)
print caesar(message, int(rotation))

print("Will exit in 1")

print("Enter message:")
message = raw_input()

print("Enter rotation:")
rotation = raw_input()

print str(rotation)
print caesar(message, int(rotation))

print("Will exit in 0")

print("Press enter to exit...")
exit = raw_input()

I need this to work for Arch Linux because I'm making it into an Arch Linux package for users to install from pacman.

GitHub