chore(deps): bump postcss-loader from 6.2.1 to 8.1.0

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 6.2.1 to 8.1.0.
- [Release notes](https://github.com/webpack-contrib/postcss-loader/releases)
- [Changelog](https://github.com/webpack-contrib/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/postcss-loader@v6.2.1...v8.1.0)

---
updated-dependencies:
- dependency-name: postcss-loader
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -50,7 +50,7 @@
     "mini-css-extract-plugin": "^2.7.6",
     "postcss": "^8.4.31",
     "postcss-flexbugs-fixes": "^5.0.2",
-    "postcss-loader": "^6.2.1",
+    "postcss-loader": "^8.1.0",
     "postcss-normalize": "^10.0.1",
     "postcss-preset-env": "^7.0.1",
     "prompts": "^2.4.2",