Bump postcss from 8.3.5 to 8.3.6 in /packages/dashboard

Bumps [postcss](https://github.com/postcss/postcss) from 8.3.5 to 8.3.6.
- [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/8.3.5...8.3.6)

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

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

packages/dashboard/package.json

@@ -23,7 +23,7 @@
     "http-status-codes": "2.1.4",
     "ky": "0.25.1",
     "next": "11.0.1",
-    "postcss": "8.3.5",
+    "postcss": "8.3.6",
     "prettier": "2.3.2",
     "pretty-bytes": "5.6.0",
     "react": "17.0.2",