Lock the XO dependency

sindresorhus · sindresorhus · commit e9187e2952c0 · 2016-12-11T02:02:27.000+01:00
diff --git a/package.json b/package.json
@@ -39,7 +39,7 @@
     "grunt-cli": "^1.2.0",
     "grunt-contrib-clean": "^1.0.0",
     "grunt-contrib-nodeunit": "^1.0.0",
-    "xo": "*"
+    "xo": "^0.16.0"
   },
   "peerDependencies": {
     "grunt": ">=0.4.0"
