Pytorch-ie

:beetle: Fixes

* save entries of `token_offset_mapping` as lists in document metadata (356) ArneBinder

* add `sum` to default aggregation functions for `LabelCountCollector` (354) ArneBinder
* upgrade `LabeledSpanLengthCollector` to `SpanLengthCollector` (352) ArneBinder
* infer labels in `LabelCountCollector` (351) ArneBinder

:beetle: Fixes

* Fix document types with partitions (349) ArneBinder
* handle `split` parameter for `DatasetDict.load_dataset()` (348) ArneBinder

* (de-)serialize `document_type` when calling `DatasetDict.(to|from)_json()` (346) ArneBinder

* `document_type` for `DocumentMetric`s (343) ArneBinder
* implement `resolve_optional_document_type()` (344) ArneBinder

* Update `hf_hub_mixin.py` to fix `push_to_hub=True` (339) ArneBinder
* skip tests that depend on the HF conll2003 dataset if that is not reachable (340) ArneBinder

:boom: Breaking Changes

* do not try to infer the `document_type` from the function in `(Iterable)Dataset.map()` (337) ArneBinder