fix: downgrade unbuild to fix cjs types output

fixes #38

unjs/unbuild#531

Author: danielwaltz

package-lock.json

@@ -70,7 +70,7 @@
     "semantic-release": "^24.2.3",
     "standard-version": "^9.5.0",
     "typescript": "~5.8.3",
-    "unbuild": "^3.5.0",
+    "unbuild": "~3.4.2",
     "vite": "^6.3.5",
     "vitest": "^3.1.3"
   },