Update package.json

Author: bermanboris

package.json

@@ -123,6 +123,7 @@
     "tslint-config-prettier": "^1.18.0",
     "tslint-config-standard": "^8.0.1",
     "typedoc": "^0.14.2",
-    "typescript": "^3.4.3"
+    "typescript": "^3.4.3",
+    "underscore.string": "^3.3.5"
   }
 }