Update some dependencies to be Python-specific.
Review Request #9526 — Created Jan. 24, 2018 and submitted
We have a couple dependencies that no longer work on older versions of
Python, which would make installation problematic for users and CI
maintenance more troublesome. We're also missing a dependency for Python
2.6 and lower.
This change adds the
argparsedependency for Python 2.6 and lower, and
paramikodependency to the latest version for each Python
version supported. It also changes the
dev-requirements.txtto choose an appropriate version for each version
of Python, using version specifiers.
Manually tested installation with Python 2.6 and 2.7.