Improve V2 workflow and make backwards compatible

[thehomebrewnerd]

V2 of the workflow changed the way that the library version number is obtained in build.sh. This change means that V2 of the workflow will not work on repos that are not set up to use pyproject.toml and setup.cfg files. V2 also assumes that a file names <libname>/version.py will be present, and this script will fail if the version number is stored elsewhere.

We should update this action to implement a better, more robust method for obtaining the version number, and also make it backward compatible, if possible, to work on repos that still utilize setup.py.