fix: 🐛 update expo install command for jest

✅ Closes: #247

Author: MatthysDev

challenges/ecosystem/05.md

@@ -116,7 +116,7 @@ Check if your test are passing with `npm run test`.
 - [ ] Install the Jest package, as well as an Expo-specific Jest preset package:
 
 ```console
-expo install jest-expo jest
+npx expo install -- --save-dev jest-expo jest
 ```
 
 Update `package.json` with a new script to run Jest