feat(deployment): integrate @astrojs/vercel as SSR adapter (#43)

This Pull request integrates the `@astrojs/vercel` as SSR adapter which
fixes the current regressed state of the initial production deployment.
This PR replaces the integration of `@astrojs/node` as SSR adapter due
to the specific requirement of deploying to Vercel.

### Changes Made

- Added the `@astrojs/vercel` module to dependencies
- Configured the integration in the `astro.config.mjs` file replacing
the configuration of `@astrojs/node` as SSR adapter

### Screenshot 

_Before_

![screenshot-jargons-dev vercel app-2024 04
17-00_37_17](https://github.com/babblebey/jargons.dev/assets/25631971/d7a5c4c7-a9a4-4356-a466-a297c6248a9a)

_After_

![image](https://github.com/babblebey/jargons.dev/assets/25631971/a4f080aa-ac3d-4ffd-b431-029ecb335010)

Author: babblebey

astro.config.mjs

@@ -2,13 +2,12 @@ import { defineConfig } from "astro/config";
 import tailwind from "@astrojs/tailwind";
 import mdx from "@astrojs/mdx";
 import react from "@astrojs/react";
-import node from "@astrojs/node";
+
+import vercel from "@astrojs/vercel/serverless";
 
 // https://astro.build/config
 export default defineConfig({
   integrations: [tailwind(), mdx(), react()],
   output: "server",
-  adapter: node({
-    mode: "standalone"
-  })
+  adapter: vercel()
 });