Update compileSdkVersion (breaks release build on latest version of Flutter)

[kwellman]

After upgrading my project to flutter 3.24, the android release build broke due to this package. It causes the error: "AAPT: error: resource android:attr/lStar not found". The issue flutter/flutter#153281 explains the error and gives a solution.

To fix it, the compileSdkVersion in build.gradle needs to be incremented to at least version 31.