[CI] Revisit CI implementation for the repository

[jspaezp]

diadem/.github/workflows/tests.yml

Line 41 in 113521f

pytest --cov=ppx tests/

There are some places where the CI can be re-organized in such way that it fits better this project.

1. Update some naming so it fits this project and not where the template came from (not a huge deal)
2. Add the current linting tools, check redundancy with flake8
3. Decide on a release schedule/release criteria.