chore(package): update ava to version 1.2.0

Closes #43

Author: greenkeeper[bot]

package.json

@@ -20,7 +20,7 @@
     "retext-smartypants": "^3.0.1"
   },
   "devDependencies": {
-    "ava": "^0.24.0",
+    "ava": "^1.2.0",
     "codecov": "^3.0.0",
     "nyc": "^11.4.1",
     "reshape": "^0.4.2",