chore: bump chromatic from 6.11.4 to 6.15.0 in /site (#5954)

Bumps [chromatic](https://github.com/chromaui/chromatic-cli) from 6.11.4 to 6.15.0.
- [Release notes](https://github.com/chromaui/chromatic-cli/releases)
- [Changelog](https://github.com/chromaui/chromatic-cli/blob/main/CHANGELOG.md)
- [Commits](https://github.com/chromaui/chromatic-cli/compare/v6.11.4...v6.15.0)

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

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

site/package.json

@@ -108,7 +108,7 @@
     "@typescript-eslint/parser": "5.45.1",
     "@xstate/cli": "0.3.0",
     "canvas": "2.10.0",
-    "chromatic": "6.11.4",
+    "chromatic": "6.15.0",
     "eslint": "8.33.0",
     "eslint-config-prettier": "8.5.0",
     "eslint-import-resolver-typescript": "3.5.0",