chore(package): update standard to version 13.1.0

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
     "mocha": "^6.0.0",
     "nyc": "^14.0.0",
     "should": "^13.0.1",
-    "standard": "^13.0.1"
+    "standard": "^13.1.0"
   },
   "dependencies": {
     "xtend": "^4.0.1"