feat: moved to pyproject.toml; closes #162

Description

Moved to pyproject.toml. This MR also changes the way BEC Widgets is installed as there is no default Python-Qt binding anymore. Instead, one has to actively select one through additional dependencies:

pip install ./[pyqt6]

or

pip install ./[pyqt5]

or combined with the dev dependencies

pip install ./[dev,pyqt6]

As it turns out, black actively checks against the supported python version and this check apparently never worked with setup.cfg. It does however work with pyproject, leading to some additional formatter changes.

Related Issues

closes #162 (closed)

Type of Change

• Removed setup files; added pyproject file
• Applied formatter
• Removed formatter configs from the ci file as they are now taken from pyproject

Potential side effects

pip install -e ./bec-widgets does not install a Python-Qt binding anymore. But I guess that's anyway better for licensing reasons.

Definition of Done

• Documentation is up-to-date.