chore: add util dev dep for browser build

Author: vasco-santos

package.json

@@ -60,7 +60,8 @@
     "chai-bytes": "~0.1.2",
     "chai-string": "^1.5.0",
     "dirty-chai": "^2.0.1",
-    "npm-run-all": "^4.1.5"
+    "npm-run-all": "^4.1.5",
+    "util": "^0.12.3"
   },
   "contributors": [
     "Vasco Santos <[email protected]>",