chore(package): update ava to version 3.8.0

Closes #3

Author: greenkeeper[bot]

package.json

@@ -7,7 +7,7 @@
     "url": "https://github.com/andrejewski/affection/issues"
   },
   "devDependencies": {
-    "ava": "^0.25.0",
+    "ava": "^3.8.0",
     "fixpack": "^2.3.1",
     "prettier": "^1.13.4",
     "standard": "^12.0.1"