Migrate to Poetry Packaging and Dependency Management

[viralogic]

Hi,

Thanks for your work on this project. I have found it useful because it is so simple to integrate.

Poetry has become the de-facto Python standard for managing dependencies and building packages. I have taken the liberty of migrating this project to Poetry and removing all the old style requirements files and setup files for packaging.

I have also removed tox.ini requirement in favor of GitHub Actions for continuous integration testing.

What changed

• migrated to Poetry for dependency management and packaging
• removed redundant requirements files and setup files.
• added GitHub Action CI
• removed tox.ini as now handled by GitHub Action
• README.md changes to mention that poetry is required when contributing.