Python 3.6 is EOL

[ppolewicz]

Screeps claims to be python-compatible, but the only version of python you can play it is so old it's illegal to code in it. There is a new version of transspiler that supports python 3.9 already, but this repository is not using it. As far as I see, there is not even a ton of changes, it's like 66 commits and 17 merges (the dabross performance patches would need to be potentially updated). Lots of modern python syntax could be enabled, python is on the hype wave, it would be cool to be able to use it with python properly.