Update README.md

Author: hieuwu

README.md

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 # just-art-android
-[![Android CI](https://github.com/hieuwu/just-art-android/actions/workflows/app-build.yml/badge.svg)](https://github.com/hieuwu/just-art-android/actions/workflows/app-build.yml)
 Android app with Art Institute of Chicago API
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+![app-cover](https://github.com/user-attachments/assets/e1af94de-d9d3-48c3-8960-7bde730ebbcd)