Bump postcss from 8.2.7 to 8.2.8 (#3507)

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.7 to 8.2.8.
- [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/8.2.7...8.2.8)

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package.json

@@ -145,7 +145,7 @@
     "node-sass-package-importer": "^5.3.2",
     "nodemon": "^2.0.7",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.2.7",
+    "postcss": "^8.2.8",
     "postcss-cli": "^8.3.1",
     "postcss-scrollbar": "^0.3.0",
     "rollup": "^2.40.0",