check for abstracts cut-and-pasted from the PDF

Ingestion (perhaps via `normalize_anth`) should check for hyphenations that indicate an abstract has been cut-and-pasted from a PDF, e.g., "pro- vides". We could probably mostly correct this automatically, though note that there are situations where the hyphen should be retained and only the space deleted (e.g., "top- selling").

[Here's an example](https://github.com/acl-org/acl-anthology/pull/665/files#diff-6361fe7f6c8b5160ffcf735c43097cf2L10941).