Update pytorch-ie 0.18.0

[ArneBinder]

This PR:

• updates the requirement for pytorch-ie to 0.18.0
• removes DocumentMetric and F1Metric and uses the implementations from pytroch-ie instead
• simplifies src.documnt.conversion.token_based_document_with_entities_and_relations_to_text_based: we use new functionality from pytorch-ie, i.e.
  • entity.copy(start=char_start, end=char_end) and
  • new_doc.add_all_annotations_from_other(doc, override_annotation_mapping={"entities": entity_map}).