chore(deps): update dependency postcss-loader to v4 (#2511)

* chore(deps): update dependency postcss-loader to v4

[skip netlify]

* Add postcss dependency

* Add postcssOptions

Co-authored-by: Renovate Bot <bot@renovateapp.com>
Co-authored-by: Young Min Kin <mail@ylem.kim>

package.json

@@ -63,7 +63,8 @@
     "mkdirp": "^1.0.4",
     "pako": "^1.0.8",
     "pnp-webpack-plugin": "^1.6.4",
-    "postcss-loader": "^3.0.0",
+    "postcss": "^7.0.32",
+    "postcss-loader": "^4.0.0",
     "postcss-preset-env": "^6.7.0",
     "prettier": "^2.0.5",
     "query-string": "^6.2.0",