Bump postcss from 8.2.5 to 8.2.6 (#33105)

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.5 to 8.2.6.
- [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/8.2.5...8.2.6)

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package.json

@@ -135,7 +135,7 @@
     "lockfile-lint": "^4.3.7",
     "nodemon": "^2.0.7",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.2.5",
+    "postcss": "^8.2.6",
     "postcss-cli": "^8.3.1",
     "rollup": "^2.38.5",
     "rollup-plugin-istanbul": "^3.0.0",