Update dependency xo to v0.31.0

Author: renovate-bot

package.json

@@ -48,7 +48,7 @@
     "microtime": "3.0.0",
     "np": "6.2.3",
     "nyc": "15.1.0",
-    "xo": "0.30.0"
+    "xo": "0.31.0"
   },
   "files": [
     "lib"