chore(package): update ava to version 3.5.1

Closes #8

Author: greenkeeper[bot]

package.json

@@ -55,7 +55,7 @@
     "LICENSE"
   ],
   "devDependencies": {
-    "ava": "1.3.0",
+    "ava": "3.5.1",
     "coveralls": "3.0.3",
     "execa": "1.0.0",
     "nyc": "13.3.0"