chore(deps-dev): bump postcss from 8.4.21 to 8.4.23

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.21 to 8.4.23.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.21...8.4.23)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -38,7 +38,7 @@
     "eslint-webpack-plugin": "^3.2.0",
     "html-webpack-plugin": "^5.5.0",
     "mini-css-extract-plugin": "^2.7.2",
-    "postcss": "^8.4.6",
+    "postcss": "^8.4.23",
     "postcss-loader": "^7.2.4",
     "prettier": "^2.8.5",
     "react-refresh": "^0.14.0",