Add support for coverage reporting

[leandro-lucarella-frequenz]

Coverage reporting can be added via pytest-cov and then visualized via codecov.

In the pyproject.toml file we should add to the dependencies:

dev-pytest = [
  "pytest == 7.3.1",
  "pytest-cov == 4.0.0",
  "...",
]

Then basically just run pytest --cov python.package.to.test in the CI and use the codecov/codecov-action to upload the reports.

• Example project: https://github.com/codecov/example-python
• Example config: https://github.com/codecov/example-python/blob/main/codecov.yml
• GitHub workflow example: https://github.com/codecov/example-python/blob/main/.github/workflows/ci.yml