Update postcss-loader to version 4.2.0

Author: depfu[bot]

package.json

@@ -22,7 +22,7 @@
     "node-sass": "^6.0.1",
     "path-complete-extname": "^1.0.0",
     "postcss": "^8.2.14",
-    "postcss-loader": "^3.0.0",
+    "postcss-loader": "^4.2.0",
     "postcss-smart-import": "^0.7.6",
     "precss": "^4.0.0",
     "resolve-url-loader": "^3.1.2",