Min/Latest Dependency Tests Need to account for platform

[scbedd]

Issue, as quoted from @chlowell

Our current cryptography requirement (in shared_requirements) is >=2.1.4. The latestdependency test lists all versions of cryptography on PyPI and installs the latest one, cryptography==3.3.1. That causes the test to fail on Python 3.5 because 3.3.1 doesn’t provide a wheel for 3.5. I suppose we could fix this by putting a conditional upper bound on the requirement. It feels like a test bug to me though—the script should install the latest version available on its current platform. Thoughts?

And I totally agree. If there isn't a simple answer, will stopgap with a conditional to get builds green.