chore(package): update ava to version 0.13.0

http://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -2,7 +2,7 @@
   "name": "postcss-selector-parser",
   "version": "1.3.3",
   "devDependencies": {
-    "ava": "^0.12.0",
+    "ava": "^0.13.0",
     "babel-cli": "^6.4.0",
     "babel-core": "^6.4.0",
     "babel-plugin-add-module-exports": "^0.1.2",