Transition package manager from pipenv to poetry

[ronnie-llamado]

Describe the solution you'd like
The transition to using poetry as the package manager for this project has started. There are still a few loose ends to tie up.

To Do

• Update GitHub Actions to use poetry (Update workflow/Makefile to use poetry #237)
• Add new GitHub Actions workflow to push package to PyPi on new tag
• Move PyPi information (version, classifiers, etc) over to pyproject.toml
• Remove extraneous pipenv files (when transition is complete)