enable py 312 and disable py38

Bugfix release for polygonizer

Hotfix for bidi incompatibility

Hotfixes for PageXML serialization

Hotfix for untagged recognition with non-standard linetypes

Robustness improvements and fixes in polygonization/extraction

Regression in container class binary dataset building

also fixes spurious metric updating during sanity checking

Hotfix for segmentation training

Hotfix for no_segmentation mode recognition

Hotfix for progress bar regression and incorrect Segmentation test