Removed Depreciations

[AbhayVAshokan]

The following usages were depreciated and were replaced suitably. It does not affect what is rendered on the screen. The new usages keeps the code safe for future users.

Theme.of(context).textTheme.title => Theme.of(context).textTheme.headline6
Theme.of(context).textTheme.subhead => Theme.of(context).textTheme.subtitle1
Theme.of(context).textTheme.body1 => Theme.of(context).textTheme.bodyText2
Theme.of(context).textTheme.headline => Theme.of(context).textTheme.headline5

The following dependencies were updated in pubspec.yaml

cupertino_icons: ^0.1.2 => ^0.1.3
fl_chart: ^0.8.6 => ^0.8.7

[yozachar]

Nice @AbhayVAshokan.

[ashishkhuraishy]

Nice one😄