Add worker versions to TranscriptionEntity

...nts/migrations/0034_transcriptionentity_worker_version.py

arkindex/documents/models.py

arkindex/documents/serializers/entities.py

arkindex/documents/tasks.py

arkindex/documents/tests/test_entities_api.py

arkindex/sql_validation/worker_results_delete_in_corpus.sql

...dex/sql_validation/worker_results_delete_under_parent.sql

...alidation/worker_results_delete_under_parent_included.sql