build(deps-dev): bump tsdown from 0.21.7 to 0.21.9

Bumps [tsdown](https://github.com/rolldown/tsdown) from 0.21.7 to 0.21.9.
- [Release notes](https://github.com/rolldown/tsdown/releases)
- [Commits](rolldown/tsdown@v0.21.7...v0.21.9)

---
updated-dependencies:
- dependency-name: tsdown
  dependency-version: 0.21.9
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

package.json

@@ -40,7 +40,7 @@
     "react": "19.2.4",
     "react-dom": "19.2.4",
     "react-test-renderer": "19.2.4",
-    "tsdown": "0.21.7",
+    "tsdown": "0.21.9",
     "typescript": "6.0.2",
     "vitest": "4.1.2"
   },