chore(package): update xo to version 0.25.4

Closes #93

Author: greenkeeper[bot]

package.json

@@ -62,7 +62,7 @@
     "eslint-plugin-promise": "4.0.1",
     "eslint-plugin-unicorn": "6.0.1",
     "nodemon": "1.19.1",
-    "xo": "0.24.0"
+    "xo": "0.25.4"
   },
   "eslintConfig": {
     "parser": "babel-eslint",