Convert away from `six` python 2 -> 3 conversion library

[matteius]

Convert away from six python 2 -> 3 conversion library

Issue description

We no longer support python 2 so including six should no longer be a requirement.

[oz123]

We will need to sieve through the vendored packages and slowly bump them up to versions that don't support Python2.

[oz123]

I already removed\bumped a few vendored libs which pulled six.
We now only have plette and pipfile which pull it.