Improve charts colors

android/gradle.properties

fastlane/metadata/android/en-US/changelogs/12.txt

fastlane/metadata/android/fr-FR/changelogs/12.txt

lib/ui/widgets/main_screen/counts_by_day_card.dart

lib/ui/widgets/main_screen/counts_by_day_chart.dart

lib/ui/widgets/main_screen/counts_by_hour_card.dart

lib/ui/widgets/main_screen/counts_by_hour_chart.dart

lib/ui/widgets/main_screen/timeline_card.dart

lib/ui/widgets/main_screen/timeline_chart_counts.dart

lib/ui/widgets/main_screen/timeline_chart_eclecticism.dart

pubspec.yaml