upgrade all packages for full support of null-safety about fluwix

[limcheekin]

Hi there,

Thanks for raising the issue. I aware that some of the modules of the project is not migrated to null-safety yet, hence the project is not sound null-safety. In fact, issue #1 is keep track the migration works. Back then one of the dependency of a module is https://pub.dev/packages/charts_flutter, hence I put the migration works on hold until charts_flutter migrated to null-safety then I continue the migration works of the project.

The charts_flutter is now null-safety, however my work priority was shifted to blockchain development few months ago, please find out more at https://limcheekin.blogspot.com/2021/07/closing-gap.html.

Hence, I will resume the work here only when I need to work on Flutter project, will close this issue as it is duplicate of issue #1.

[limcheekin]

The app is now sound null safety :)