Fix Incorrect Python Version Detection in Source Code

[Fazzioni]

The previous implementation of the Python version detection logic incorrectly checked for Python 2 print statements by searching for the substring "print " in the source code. This approach could lead to false positives when the word print appeared inside comments or strings, causing incorrect detection of Python 2 syntax even when the code was actually using Python 3.

Example of problematic code:

# This is a comment that mentions print
print("Hello, World!")  # This is Python 3 syntax

In the above example, the previous logic would mistakenly interpret this as Python 2 code because it found "print " in the comment.

Fix Overview:
The detection mechanism was improved by utilizing Python's tokenize module to properly parse the source code into tokens, ignoring comments and strings.
Now, the code correctly differentiates between print as a Python 2 statement and print as a Python 3 function by checking if it is followed by a parenthesis (().