chore(package): update ava to version 2.0.0

Author: greenkeeper[bot]

package.json

@@ -14,7 +14,7 @@
     "lodash.uniqby": "^4.7.0"
   },
   "devDependencies": {
-    "ava": "^1.0.1",
+    "ava": "^2.0.0",
     "codecov": "^3.0.0",
     "nyc": "^14.0.0",
     "semantic-release": "^15.0.0",