update method
Rebuilds GetBuilder each time you call update();
Can take a List of ids, that will only update the matching
GetBuilder( id: ),
ids can be reused among GetBuilders like group tags.
The update will only notify the Widgets, if condition is true.
Implementation
void update([List<Object>? ids, bool condition = true]) {
  if (!condition) {
    return;
  }
  if (ids == null) {
    refresh();
  } else {
    for (final id in ids) {
      refreshGroup(id);
    }
  }
}