chore: update postcss-loader

Author: alexander-akait

package-lock.json

@@ -69,7 +69,7 @@
     "lint-staged": "^7.2.0",
     "memory-fs": "^0.4.1",
     "nsp": "^3.2.1",
-    "postcss-loader": "^2.1.6",
+    "postcss-loader": "^3.0.0",
     "postcss-preset-env": "^5.2.1",
     "pre-commit": "^1.2.2",
     "prettier": "^1.13.7",