Add extra safety checks for proto pollution (#20396)

Co-authored-by: Gal Zahavi <38544478+galz10@users.noreply.github.com>

packages/cli/src/utils/deepMerge.ts

@@ -30,7 +30,7 @@ function mergeRecursively(
   for (const key of Object.keys(source)) {
     // JSON.parse can create objects with __proto__ as an own property.
     // We must skip it to prevent prototype pollution.
-    if (key === '__proto__') {
+    if (key === '__proto__' || key === 'constructor' || key === 'prototype') {
       continue;
     }
     const srcValue = source[key];