chore: bump chromatic from 6.19.9 to 6.20.0 in /site (#8667)

Bumps [chromatic](https://github.com/chromaui/chromatic-cli) from 6.19.9 to 6.20.0.
- [Changelog](https://github.com/chromaui/chromatic-cli/blob/main/CHANGELOG.md)
- [Commits](https://github.com/chromaui/chromatic-cli/compare/v6.19.9...v6.20.0)

---
updated-dependencies:
- dependency-name: chromatic
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

site/package.json

@@ -129,7 +129,7 @@
     "@typescript-eslint/eslint-plugin": "5.62.0",
     "@typescript-eslint/parser": "5.62.0",
     "@xstate/cli": "0.5.2",
-    "chromatic": "6.19.9",
+    "chromatic": "6.20.0",
     "eslint": "8.44.0",
     "eslint-config-prettier": "8.8.0",
     "eslint-import-resolver-typescript": "3.5.5",