ShapeOut 2.19.0

Thanks to @RaghavaAlajangi who implemented the Young's modulus look-up-table selection in the graphical user interface and while doing so also did most of the work upgrading the GUI toolkit from Qt5 to Qt6.
I also added a preferences section for adding S3 object storage access credentials. Previously you had to use a workaround with environment variables to achieve this. I also added the dclab[s3] extras to the install dependencies which adds boto3 (which is now also part of the binary releases).

Detailed list of changes

• feat: support accessing private S3 basins (#174)
• enh: enable lut selection in analysis view plots (#71)
• fix: only allow user to choose "R.exe" in R binary manual search (#173)
• enh: correctly show system R binary in settings
• ref: migrate from pyqt5 to pyqt6 (#165)
• ref: migrate from pkg_resources to importlib.resources (#155)
• setup: support Python 3.12
• setup: new dependency "boto3" via "dclab[s3]""