Consider dropping python 2 compatibility

[Ben Brown]

python 2 reached EOL in the beginning of 2020, dropping compat code would result in a cleaner code base, making it easier to maintain.

I'm happy to contribute towards this effort, though I'm hesitant to make such a drastic change if it isn't welcome.

[Refael Ackermann]

I have a ton of respect to the original authors, but since Google migrated from GYP to GN this repo has been mostly unmaintained.

Several nodejs project still depend on GYP and maintain a fork at:

https://github.com/nodejs/gyp-next
and my fork:

https://github.com/refack/GYP3