Update tools

[MatsG23]

This pull request includes the changes from the migrateToMaterial3 branch. Do not merge before #103 is merged!

• upgrade Flutter dependencies (except http due to a raised sdk version I cannot use due to the Flutter 3.16 issue)
• upgrade Gradle to version 8.5
• upgrade Kotlin version to 1.9.21
• setup flutter_local_notifications correctly (desugaring enabled and more receivers in the manifest file - see plugin documentation)
• raise compileSdk and targetSdk version to 34 (A14)
• remove package name from manifest file (deprecated, set in android/app/build.gradle)