fix: playlist creation

[lucagoslar]

This PR fixes the playlist creation on mobile devices. (Find the working web app implementation here and the affected API documentation here.)

Since most dependencies, if not all, are outdated, I had issues building the application. Below, you can find instructions to solve those issues on a machine running the latest Xcode and iOS simulator versions.

flutter pub upgrade
sed -i '' 's/fading_edge_scrollview: \^3\.0\.0/fading_edge_scrollview: \^4\.1\.1/' pubspec.yaml