[paskino]

Enables use of Qt6 in iDVC:

• uses QtPy abstraction layer
• uses pyside6 in CI
• removes qdarkstyle, see qdarkstyle has not been updated since 2023 eqt#190
• modify yaml file to create a working development environment

Depends on:

• eqt remove qdarkstyle, run unittest offscreen and test pyside6 eqt#191
• CILViewer PySide6 in CI and preview dialog cannot be closed on macos CILViewer#491

Testing locally

git clone git@github.com:TomographicImaging/iDVC.git
cd iDVC
git checkout migrate_to_qt6_master
conda env create -n idvc_qt6 -f recipe/environment_qt6.yml
conda activate idvc_qt6
pip install .
idvc --log debug

Tested:

• locally on macos
• locally on windows
• locally on linux