migrate to sqlite3: ^3.0.0

[stevenctl]

Currently this package (for flutter apps) relies on sqlite3_flutter_libs.

sqlite3 now uses build hooks so there is no need to pull the packages in separately

https://pub.dev/packages/sqlite3
https://pub.dev/packages/sqlite3_flutter_libs
https://github.com/simolus3/sqlite3.dart/blob/main/UPGRADING_TO_V3.md

[simolus3]

Thanks for opening the issue, I agree that we should upgrade to sqlite3: ^3.0.0. At the moment however, there are some remaining issues with build hooks and code assets (see simolus3/sqlite3.dart#336).

These issues need to be fixed in Flutter before using build hooks is a good option. Our plan is to migrate this package (and other components of the PowerSync Dart/Flutter SDK) to build hooks once these issues have been fixed on a stable Flutter release.