Ocrmypdf-papermerge

- Dependencies updates. Use Python 3.13.

- OCR per page (pass one `uuid` instead of `uuids` list)

- Fix Image.ANTIALIAS deprication issue

Changed

- minor adjustment for new plugin interface i.e. incl.
``thresholding=options.tesseract_thresholding`` argument in ``tesseract.generate_hocr``

Changed

- readme field added to pyproject.toml file

Added

- changelog.md file

Changed

- use pytest instead of unittest
- use poetry for dependencies management
- updated dependencies