Readthedocs.io dependencies are unmanaged

[tpears]

Currently the docs/requirements.txt file is static which could allow the dependency versions to fall behind. This file is used by the readthedocs.io pipeline to start a virtual environment with the required dependencies to build the documentation out of this repo for hosting on that site. Any automation to check for and deploy the latest version of those dependencies should exist in that pipeline instead of the github pipeline.