What is the release date of the bonus interview with Peter Purves?
CREATE TABLE "television_soundtracks" (
  "story_num" real,
  "title" text,
  "doctor" text,
  "narrator" text,
  "format" text,
  "release_date" text,
  "notes" text
);
SELECT "release_date" FROM "television_soundtracks" WHERE "notes"='Bonus interview with Peter Purves';