make tsdown version happy default

Author: pcarleton

package-lock.json

@@ -38,7 +38,7 @@
     "jest": "^29.7.0",
     "prettier": "3.6.2",
     "ts-jest": "^29.1.1",
-    "tsdown": "^0.16.2",
+    "tsdown": "^0.15.12",
     "tsx": "^4.7.0",
     "typescript": "^5.5.4",
     "typescript-eslint": "^8.0.0"