fix: use generic for valueWhen in ResponsiveValue

Author: Vinzent03

lib/responsive_value.dart

@@ -18,7 +18,7 @@ import 'responsive_framework.dart';
 class ResponsiveValue<T> {
   T? value;
   final T defaultValue;
-  final List<Condition> valueWhen;
+  final List<Condition<T>> valueWhen;
 
   final BuildContext context;