chore(deps-dev): bump @spotify/prettier-config in /microsite

Bumps [@spotify/prettier-config](https://github.com/spotify/web-scripts) from 8.0.0 to 9.0.0.
- [Release notes](https://github.com/spotify/web-scripts/releases)
- [Changelog](https://github.com/spotify/web-scripts/blob/master/CHANGELOG.md)
- [Commits](https://github.com/spotify/web-scripts/compare/v8.0.0...v9.0.0)

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

microsite/package.json

@@ -14,7 +14,7 @@
     "rename-version": "docusaurus-rename-version"
   },
   "devDependencies": {
-    "@spotify/prettier-config": "^8.0.0",
+    "@spotify/prettier-config": "^9.0.0",
     "docusaurus": "^2.0.0-alpha.66",
     "js-yaml": "^3.14.0",
     "prettier": "^2.0.5"