Bump postcss from 8.5.5 to 8.5.6

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.5 to 8.5.6.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.5.5...8.5.6)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.6
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

package.json

@@ -56,7 +56,7 @@
     "file-loader": "^6.2.0",
     "lato-font": "^3.0.0",
     "mini-css-extract-plugin": "^2.9.2",
-    "postcss": "^8.5.5",
+    "postcss": "^8.5.6",
     "postcss-loader": "^8.1.1",
     "postcss-scss": "^4.0.9",
     "regenerator-runtime": "^0.14.1",