build(deps): bump react-router-dom in /showcase/playground-showcase

Bumps [react-router-dom](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router-dom) from 6.4.2 to 6.4.3.
- [Release notes](https://github.com/remix-run/react-router/releases)
- [Changelog](https://github.com/remix-run/react-router/blob/main/packages/react-router-dom/CHANGELOG.md)
- [Commits](https://github.com/remix-run/react-router/commits/react-router-dom@6.4.3/packages/react-router-dom)

---
updated-dependencies:
- dependency-name: react-router-dom
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

showcase/playground-showcase/package-lock.json

@@ -12,7 +12,7 @@
     "react": "17.0.2",
     "react-ace": "10.1.0",
     "react-dom": "17.0.2",
-    "react-router-dom": "6.4.2"
+    "react-router-dom": "6.4.3"
   },
   "devDependencies": {
     "@types/dompurify": "^2.3.4",