Prepare release

[simolus3]

This prepares a minor release of the PowerSync SDK for Dart. I have changed the powersync and powersync_sqlcipher packages to use an exact version dependency on powersync_core. In the future, this means that downgrading the user-facing package will also downgrade the powersync_core version. Actually that seems to break the dart pub lish --dry-run check, so let's keep that as-is for now until there's a workaround for that.

Changes this the last release are:

• Sync progress
• New schema options (tracking metadata, previous values and the option to skip creating CRUD entries for empty updates)