Add compatibility with Android Gradle Plugin 8.0

[asaarnak]

Add a namespace attribute to the Android build.gradle, for compatibility with Android Gradle Plugin 8.0.
See:
flutter/packages@6284c2d

[dnys1]

Thanks for the heads up, @asaarnak! We are working on a fix now 👍

[dnys1]

This fix has been released in v1.1.0