Upgrade and unpin remaining dependencies

[WadeBarnes]

An overview of all installed, referenced, and required PyPI packages can be found here: Hyperledger Indy-Plenum | Dependency management Ubuntu 20

As discussed here, Issue #1544, there are still several dependencies that need to be upgraded following the initial Ubuntu 20.04 release.

Where possible the dependencies should be upgraded individually to reduce the scope of the work, and a separate issue linking back to this one should be created to track the work.