Upgrade postcss-reporter to ^4.0.0

Author: RyanZim

package.json

@@ -25,7 +25,7 @@
     "ora": "^1.1.0",
     "postcss": "^6.0.1",
     "postcss-load-config": "^1.1.0",
-    "postcss-reporter": "^3.0.0",
+    "postcss-reporter": "^4.0.0",
     "read-cache": "^1.0.0",
     "yargs": "^8.0.1"
   },