CI/CD: Automate PyPi & ReadTheDocs releases

[esqew]

Breaking this out from the issue in which it was initially brought up - it may behoove us to build additional CI/CD steps and change the branching strategy ever so slightly to prepare releases in a devel or version-specific branch, then do releases automatically off of merges of these branches to master.

My plan at the moment is to build the foundation of the additional workflow in a new branch, and then @j-andrews7 you and I can discuss best path forward (adding PyPi & ReadTheDocs secrets to CI/CD config) from there.

(Part of my homework here is also to get myself better acquainted with ReadTheDocs since I haven't used it before.)