chore(package): update ava to version 0.25.0

Author: greenkeeper[bot]

package.json

@@ -60,7 +60,7 @@
   },
   "devDependencies": {
     "autoprefixer": "7.2.5",
-    "ava": "0.23.0",
+    "ava": "0.25.0",
     "coveralls": "2.13.2",
     "execa": "0.9.0",
     "nyc": "11.4.1",