drop Python2.7 WIP, trim usage of "six"

[a-detiste]

Hi,

I think that if project does not support Python2.7 anymore, six should be completely removed.

Let's start

https://wiki.debian.org/Python3-six-removal

[bitwiseman]

@a-detiste
Please continue. I fully support this effort.

[cclauss]

https://pypi.org/project/pyupgrade can help by automating many transformations.

[Anutrix]

@a-detiste Based on the CI failures, they look like formatting and newline differences. Is there any other blocker?

[a-detiste]

I m on Holliday. I don't remember any of these hundreds similar PR, but this looks pretty conservative.

[Anutrix]

@a-detiste I would happy to make an MR with same changes(and minor pipeline fixes) with you as co-author, if you are still busy. It's cool if you want to take it up when you are back too.
Hope you enjoyed(or are enjoying) in your vacation. Sry about this knock.

[a-detiste]

I would happy to make an MR with same changes(and minor pipeline fixes) with you as co-author

Hi, It's realy hard for me to resume this. I would be pleased that you pick it up.

I don't really care aboout the attribution of my changes.