* Result of black 23.1
* Update target to Python 3.7
* Switch flake8 to ruff
* Configure isort
* Configure isort
* Apply isort with line limit
* Put the right black version
* adapt black in check copies
* Fix copies
* add LUKE models for downstream tasks
* add new LUKE models to docs
* fix typos
* remove commented lines
* exclude None items from tuple return values
* add a test for a word only input
* make LukeForMaskedLM work without entity inputs
* update test
* add LukeForMaskedLM to MODEL_FOR_MASKED_LM_MAPPING_NAMES
* restore pyproject.toml
* empty line at the end of pyproject.toml