Add CI for PRs and release

[fruch]

for python-driver, I have some mileage on how to use github actions, building and testing in multiple OS and even multiple architectures

and handle the release in more automated fashion (into PyPi)

I've described it a bit here: https://fruch.github.io/2020/12/29/github-actions

I think the Jenkinsfile file from this repo can be kind of a guideline for that (how it was handled by datastax)

[Jasperav]

This is how the Rust Scylla driver implemented the CI: https://github.com/scylladb/scylla-rust-driver/blob/main/.github/workflows/rust.yml