v0.2.0

Changed:

• adapt to (and require) ocrd>=3.0
• switched to pyproject.toml build, tracking version via ocrd-tool.json
• from_coco: allow file path as basename (directory part inferred)
• from_coco: add parameter categorydict (instead of fixed PubLayNet mapping),
  but keep source=PAGE override in place

Fixed:

• from_coco: allow empty (unannotated) pages