Update next config file format

next.config.mjs

@@ -1,6 +1,6 @@
-import type { NextConfig } from "next";
+/** @type {import('next').NextConfig} */
 
-const nextConfig: NextConfig = {
+const nextConfig = {
   /* config options here */
   typescript: {
     // !! WARN !!

tsconfig.json

@@ -22,6 +22,6 @@
       "@/*": ["./src/*"]
     }
   },
-  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts"],
+  "include": ["next-env.d.ts", "**/*.ts", "**/*.tsx", ".next/types/**/*.ts", "next.config.mjs"],
   "exclude": ["node_modules"]
 }