Drop python2.6?

[asottile]

Python2.6 had been end of life for ~3 years, our master build is currently failing because flake8 has dropped support. I think we probably should as well? (or at least stop testing against it?)

[dahlia]

It'd be better to stop linting against 2.6 whether we drop 2.6 support or not.

[dahlia]

There's no strong reason to support 2.6. When I started the project, popular Python libraries supported 2.6, so I decided to support 2.6 too. I've never used 2.6 for about 6 years. I think it's okay to drop 2.6 support now.

[asottile]

+1, I'll remove explicit 2.6 support