chore(package): update ava to version 0.18.2 (#22)

Author: greenkeeper[bot]

package.json

@@ -8,7 +8,7 @@
   },
   "bugs": "https://github.com/static-dev/source-loader/issues",
   "devDependencies": {
-    "ava": "^0.17.0",
+    "ava": "^0.18.2",
     "coveralls": "2.x",
     "nyc": "10.1.2",
     "standard": "8.6.0",