Bump @atlaskit/tree from 8.8.8 to 8.8.9 (#8359)

Bumps [@atlaskit/tree](https://bitbucket.org/atlassian/atlassian-frontend-mirror) from 8.8.8 to 8.8.9.
- [Commits](https://bitbucket.org/atlassian/atlassian-frontend-mirror/commits)

---
updated-dependencies:
- dependency-name: "@atlaskit/tree"
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

package.json

@@ -36,7 +36,7 @@
   "repository": "https://github.com/pixiebrix/pixiebrix-extension",
   "dependencies": {
     "@apidevtools/json-schema-ref-parser": "^10.1.0",
-    "@atlaskit/tree": "^8.8.8",
+    "@atlaskit/tree": "^8.8.9",
     "@cfworker/json-schema": "^1.12.8",
     "@datadog/browser-logs": "^5.16.0",
     "@datadog/browser-rum": "^5.16.0",