Bump postcss-loader from 6.1.1 to 6.2.0 (#717)

Bumps [postcss-loader](https://github.com/webpack-contrib/postcss-loader) from 6.1.1 to 6.2.0.
- [Release notes](https://github.com/webpack-contrib/postcss-loader/releases)
- [Changelog](https://github.com/webpack-contrib/postcss-loader/blob/master/CHANGELOG.md)
- [Commits](webpack-contrib/postcss-loader@v6.1.1...v6.2.0)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package.json

@@ -24,7 +24,7 @@
     "fibers": "5.0.0",
     "mini-css-extract-plugin": "2.4.2",
     "postcss": "8.3.9",
-    "postcss-loader": "6.1.1",
+    "postcss-loader": "6.2.0",
     "sass": "1.43.2",
     "sass-loader": "12.2.0",
     "stylelint": "13.13.1",