Update Pylint

[nickzuber]

Our current version of pylint is slightly out of date and we're missing out on some bug fixes from the newer versions.

❯ pylint --version
pylint 1.6.5, 
astroid 1.4.0

One example is #394 (diff)
in our code where there's a problem with type annotating tuples. More about that particular issue can be found at pylint-dev/pylint#1212

We should update pylint at some point and then remove the disable workarounds. The particular issue mentioned here looks like it was fixed in version 1.5 for astroid.

[cmcginty]

I did a pylint upgrade for werk a while back. See https://github.com/box/werk/pull/868
The one thing missing however was pinning astroid and isort.