Unittests for Taskmodule

[ChristophAlt]

• Unittests for Taskmodule
• Improve configuration of pytest and isort
• Check examples with mypy
• Fix: transformer span classification should only return the probability of the predicted label
• Fix: Taskmodule should return documents in sorted order in all cases

[ArneBinder]

Looks very good! just one minor

[ArneBinder]

Can we rename documents to document_mapping?

Suggested change

	documents: Dict[Document, Document] = {}
	for encoding in encodings:
	if encoding.document not in documents:
	documents[encoding.document] = encoding.document
	all_documents = list(documents.values())
	document_mapping: Dict[Document, Document] = {}
	for encoding in encodings:
	if encoding.document not in document_mapping:
	document_mapping[encoding.document] = encoding.document
	all_documents = list(document_mapping.values())

[ChristophAlt]

Fixed.