Question: For the movie in which Tress MacNeille was the voice actor for its character "Hyacinth Hippo", what was the release date of that movie?
SQL: SELECT T1.release_date FROM characters AS T1 INNER JOIN `voice-actors` AS T2 ON T2.movie = T1.movie_title WHERE T2.character = 'Hyacinth Hippo' AND T2.`voice-actor` = 'Tress MacNeille'