remove unused vercel.json file

vercel.json

@@ -1,29 +0,0 @@
-{
-  "headers": [
-    {
-      "source": "/(.*)",
-      "headers": [
-        {
-          "key": "Strict-Transport-Security",
-          "value": "max-age=31536000; includeSubDomains; preload"
-        },
-        {
-          "key": "Content-Security-Policy",
-          "value": "default-src 'self'; img-src 'self' data:; script-src 'self' https://analytics.ahrefs.com 'unsafe-inline'; style-src 'self' 'unsafe-inline'; font-src 'self' https://fonts.googleapis.com https://fonts.gstatic.com; connect-src 'self'; frame-ancestors 'self'; base-uri 'self';"
-        },
-        {
-          "key": "X-Content-Type-Options",
-          "value": "nosniff"
-        },
-        {
-          "key": "X-Frame-Options",
-          "value": "SAMEORIGIN"
-        },
-        {
-          "key": "Referrer-Policy",
-          "value": "no-referrer-when-downgrade"
-        }
-      ]
-    }
-  ]
-}