Check type before sending #value message to predicate

The previous implementation was giving for granted that every predicate
respond  to `#value`, but that doesn't seem to be the case at least when
having a `Arel::SelectManager`.

by simply inverting the terms of the existing AND check we can fix the issue
without introducing unknown side effects.

lib/ransack/nodes/condition.rb

@@ -339,7 +339,7 @@ def in_predicate?(predicate)
       end
 
       def casted_array?(predicate)
-        predicate.value.is_a?(Array) && predicate.is_a?(Arel::Nodes::Casted)
+        predicate.is_a?(Arel::Nodes::Casted) && predicate.value.is_a?(Array)
       end
 
       def format_values_for(predicate)