Fix GH action workflows for py2.7 deprecation

[bjester]

Summary

• Updates Morango's python2 linting to be functional
• Updates workflows to have skip checks in each step, to prevent situations for 'waiting to be queued' checks
• Fixes other related issues

[rtibbles]

Looks like the matrixing worked, but now something is breaking in imports in tests, presumably new things in the stdlib not in py3.4?

[bjester]

Looks like the matrixing worked, but now something is breaking in imports in tests, presumably new things in the stdlib not in py3.4?

Yeah the test.support backport just needed to be installed, which left the more troublesome combination for 3.4 + crypto. The package repositories are no longer live for the most recent python image, as it's beyond LTS. I guess that's reason enough to drop 3.4? with crypto at the least.

[rtibbles]

Yeah, 3.4 is a massive pain, 3.5 is tricky, and 2.7 zombies on!