GHSA-97qj-x29f-37w7: NLTK: Entity-expansion DoS (billion laughs) via remaining raw ElementTree parses

Several XML parsing sites in NLTK still used `xml.etree.ElementTree` directly, which honours ` ` declarations in a document's internal DTD subset. A crafted document a few hundred bytes long can expand to megabytes in memory (each nesting level multiplies by ten), a denial-of-service. Affected call sites ( ' for i in range(1, levels+1)) return f' {d}]> &e{levels}; ' ET.fromstring(bomb(5)) # -> element whose .text is 1,000,000 chars ``` ### 2. …