Build(deps-dev): Bump postcss from 8.2.7 to 8.2.8 (#366)

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](postcss/postcss@8.2.7...8.2.8)

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

package.json

@@ -69,7 +69,7 @@
     "mocha": "^8.3.1",
     "node-sass": "^5.0.0",
     "npm-run-all": "^4.1.5",
-    "postcss": "^8.2.7",
+    "postcss": "^8.2.8",
     "prettier": "^2.2.1",
     "sass": "^1.32.8",
     "stylelint": "^13.12.0",