fix: change extension in tsup config

Author: aj-may

tsup.config.ts

@@ -1,7 +1,7 @@
 import { defineConfig } from "tsup";
 
 export default defineConfig({
-  entry: ["src/index.ts", "src/next/index.ts", "src/express/index.tsx"],
+  entry: ["src/index.ts", "src/next/index.ts", "src/express/index.ts"],
   splitting: false,
   sourcemap: true,
   dts: true,