chore(package): update ava to version 3.8.2

Closes #47

Author: greenkeeper[bot]

package.json

@@ -27,7 +27,7 @@
     "through2": "^3.0.0"
   },
   "devDependencies": {
-    "ava": "^2.0.0",
+    "ava": "^3.8.2",
     "codecov": "^3.2.0",
     "concat-stream": "^2.0.0",
     "nyc": "^15.0.0",