Update ava to the latest version 🚀 (#33)

Update ava to the latest version 🚀

Author: WindomZ

package.json

@@ -41,7 +41,7 @@
     "shelljs": "^0.8.3"
   },
   "devDependencies": {
-    "ava": "^1.2.1",
+    "ava": "^2.0.0",
     "coveralls": "^3.0.2",
     "eslint": "^5.14.0",
     "eslint-config-prettier": "^4.0.0",