Update postcss-cli to the latest version 🚀 (#194)

Author: greenkeeper[bot]

package.json

@@ -40,7 +40,7 @@
     "hugo-bin": "^0.19.0",
     "jest-cli": "^22.0.0",
     "nps": "^5.7.1",
-    "postcss-cli": "^4.1.0",
+    "postcss-cli": "^5.0.0",
     "postcss-import": "^11.0.0",
     "stylelint": "^8.3.1",
     "stylelint-config-standard": "^18.0.0",