text: Title: Move pytest config to pyproject.toml
  Body: Suggestion:
  By moving the pytest configuration to `pyproject.toml` it would be possible to remove the `pytest.ini` file.
  
  Note that the [pyproject support](https://docs.pytest.org/en/stable/customize.html#pyproject-toml) was included in pytest version 6.0 and I'm not sure if there is a specific reason (e.g. dependency conflict) that makes it impossible to update pytest right now.