Update postcss.config.mjs file

Attempt to fix the following error:
#5 13.62 Error: It looks like you're trying to use tailwindcss directly as a PostCSS plugin. The PostCSS plugin has moved to a separate package, so to continue using Tailwind CSS with PostCSS you'll need to install @tailwindcss/postcss and update your PostCSS configuration.

postcss.config.mjs

@@ -1,7 +1,8 @@
 /** @type {import('postcss-load-config').Config} */
 const config = {
   plugins: {
-    tailwindcss: {},
+    '@tailwindcss/postcss': {},
+    autoprefixer: {}
   },
 };