Fix typings

Author: stefanoverna

packages/html-to-structured-text/package.json

@@ -35,7 +35,6 @@
   },
   "dependencies": {
     "datocms-structured-text-utils": "^5.1.16",
-    "extend": "^3.0.2",
     "hast-util-from-dom": "^3.0.0",
     "hast-util-from-parse5": "^6.0.1",
     "hast-util-has-property": "^1.0.4",