Fix Vercel deployment: remove conflicting builds property, use functions only

Author: bennytobby

vercel.json

@@ -1,11 +1,11 @@
 {
   "version": 2,
-  "builds": [
-    {
-      "src": "server.js",
-      "use": "@vercel/node"
+  "functions": {
+    "server.js": {
+      "runtime": "@vercel/node",
+      "maxDuration": 30
     }
-  ],
+  },
   "routes": [
     {
       "src": "/api-docs(.*)",
@@ -18,12 +18,5 @@
   ],
   "env": {
     "NODE_ENV": "production"
-  },
-  "functions": {
-    "server.js": {
-      "maxDuration": 30
-    }
-  },
-  "buildCommand": "npm install",
-  "outputDirectory": "."
+  }
 }