Bump postcss from 8.2.7 to 8.2.8 (#566)

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>

Author: dependabot[bot]

package.json

@@ -23,7 +23,7 @@
     "css-loader": "5.1.1",
     "fibers": "5.0.0",
     "mini-css-extract-plugin": "1.3.9",
-    "postcss": "8.2.7",
+    "postcss": "8.2.8",
     "postcss-loader": "5.1.0",
     "sass": "1.32.8",
     "sass-loader": "11.0.1",