feat: auto-refresh widget colors when the theme is change by the user

refilc/lib/theme/observer.dart

@@ -1,4 +1,20 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
+import 'package:home_widget/home_widget.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+
+Future<bool?> updateWidget() async {
+  try {
+    return HomeWidget.updateWidget(name: 'widget_timetable.WidgetTimetable');
+  } on PlatformException catch (exception) {
+    if (kDebugMode) {
+      print('Error Updating Widget After changeTheme. $exception');
+    }
+  }
+  return false;
+}
 
 class ThemeModeObserver extends ChangeNotifier {
   ThemeMode _themeMode;
@@ -13,6 +29,7 @@ class ThemeModeObserver extends ChangeNotifier {
   void changeTheme(ThemeMode mode, {bool updateNavbarColor = true}) {
     _themeMode = mode;
     _updateNavbarColor = updateNavbarColor;
+    if (Platform.isAndroid) updateWidget();
     notifyListeners();
   }
 }