Create Github Action pytests

[erancx]

On a pull_request a github action will execute and do the following:

1. Run on ubuntu-latest (and we can also run it on Windows, MacOS for extended coverage)
2. Install multiple Python versions (3.7, 3.8, 3.9 etc)
3. Install python dependencies
4. Run flake8 on the code to find Python syntax errors or undefined names
5. Run Pytest
6. Upload artifact from workflow to shared data (optional)