style: disable debug banner in MaterialApp

lib/main.dart

@@ -39,6 +39,7 @@ class MainApp extends StatelessWidget {
       create: (context) => locator<AppBloc>()..add(InitLocaleEvent()),
       child: BlocBuilder<AppBloc, AppState>(
         builder: (context, state) => MaterialApp.router(
+          debugShowCheckedModeBanner: false,
           theme: MyTheme.light,
           darkTheme: MyTheme.dark,
           themeMode: ThemeService.getTheme(),