chore(deps): update dependency tsdown to v0.21.9

Author: renovate[bot]

package.json

@@ -40,7 +40,7 @@
     "knip": "6.4.1",
     "lint-staged": "16.4.0",
     "prettier": "3.8.3",
-    "tsdown": "0.21.8",
+    "tsdown": "0.21.9",
     "typescript": "6.0.3",
     "vitest": "4.1.4"
   },