Bump postcss-loader from 8.1.1 to 8.2.0

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 8.1.1 to 8.2.0.
- [Release notes](https://github.com/webpack-contrib/postcss-loader/releases)
- [Changelog](https://github.com/webpack-contrib/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/postcss-loader/compare/v8.1.1...v8.2.0)

---
updated-dependencies:
- dependency-name: postcss-loader
  dependency-version: 8.2.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

package.json

@@ -13,7 +13,7 @@
     "@vuepress/bundler-webpack": "2.0.0-rc.2",
     "@vuepress/plugin-back-to-top": "^2.0.0-rc.3",
     "@vuepress/plugin-search": "2.0.0-rc.3",
-    "postcss-loader": "^8.0.0",
+    "postcss-loader": "^8.2.0",
     "prettier": "^3.6.2",
     "sass": "^1.51.0",
     "sass-loader": "^14.2.0",