ADB backup - check for Android 12.0 Snow Cone

[upintheairsheep]

Android 12.0 “Snow Cone” disables backups on apps on Snow Cone’s API level. You should put a warning for that.

[mattiaepi]

Thanks for noticing, but this is outside the scope of the project.
There are so many differences in how ADB Backup is managed in different Android versions, and probably it will be removed in future versions.