fix(ci): update node version of preview github action (#57)

* chore: update node version for preview

* chore: update readme

Author: wataru-maeda

.github/workflows/preview.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Setup Node
         uses: actions/setup-node@v2
         with:
-          node-version: 16.x
+          node-version: 20.x
           cache: npm
 
       - name: Setup Expo

README.md

@@ -1,4 +1,4 @@
-<img src='https://github.com/wataru-maeda/react-native-boilerplate/blob/main/__DELELE_ME__/banner.png' width='400'>
+<img src='https://github.com/wataru-maeda/react-native-boilerplate/blob/main/__DELELE_ME__/banner.png' width='600'>
 
 ![CI](https://github.com/wataru-maeda/react-native-boilerplate/actions/workflows/preview.yml/badge.svg)
 ![CI](https://github.com/wataru-maeda/react-native-boilerplate/actions/workflows/test.yml/badge.svg)