fix(create-qwik): add missing execa dependency

After PR QwikDev#8103 migrated from CJS to ESM, the execa package was marked
as external in the esbuild config but was not declared as a dependency
in create-qwik's package.json.

This caused 'Cannot find package execa' error when running:
npx create-qwik@2.0.0-beta.15

Fixes the runtime error by adding execa to dependencies.

Author: JerryWu1234

packages/create-qwik/package.json

@@ -5,6 +5,9 @@
   "author": "Qwik Team",
   "bin": "./create-qwik.mjs",
   "bugs": "https://github.com/QwikDev/qwik/issues",
+  "dependencies": {
+    "execa": "9.6.0"
+  },
   "devDependencies": {
     "@clack/prompts": "0.11.0",
     "@types/yargs": "17.0.33",