[nextjs] Use config to set HTTP Server header

[According to Next.js maintainers][suggestion], this can improve
performance:

> If you only need custom headers, you might see better performance by
> using the `headers` option in `next.config.js` instead of middleware.

[suggestion]: vercel/next.js#75930 (reply in thread)

Author: jonathanhefner

frameworks/TypeScript/nextjs/middleware.ts

@@ -2,6 +2,17 @@ import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
   output: "standalone",
+
+  async headers() {
+    return [
+      {
+        source: "/(.*?)",
+        headers: [
+          { key: "Server", value: "Next.js" },
+        ],
+      },
+    ]
+  },
 };
 
 export default nextConfig;