chore: fix build

Author: antfu

build.config.ts

@@ -1,9 +1,10 @@
 import { defineBuildConfig } from "unbuild";
 
 export default defineBuildConfig({
-  entries: [
-    "src/index",
-    "src/helpers"
-  ],
+  entries: ["src/index", "src/helpers"],
   externals: ["@babel/types"],
+  declaration: true,
+  rollup: {
+    emitCJS: true,
+  },
 });