chore(package): update xtend to version 4.0.2

Author: greenkeeper[bot]

package.json

@@ -30,6 +30,6 @@
     "standard": "^12.0.0"
   },
   "dependencies": {
-    "xtend": "^4.0.1"
+    "xtend": "^4.0.2"
   }
 }