🔍 test: Upgrade ava.

Author: make-github-pseudonymous-again

package.json

@@ -11,7 +11,8 @@
       "@babel/polyfill",
       "@babel/register"
     ],
-    "timeout": "1m"
+    "timeout": "1m",
+    "concurrency": 8
   },
   "babel": {
     "presets": [
@@ -67,7 +68,7 @@
     "build": "babel src -d lib",
     "cover": "nyc --reporter=lcov npm test",
     "prepublish": "npm run build",
-    "test": "ava --concurrency 8",
+    "test": "ava",
     "esdoc": "esdoc"
   }
 }