[FIX] Pluck columns should correctly casts types when using postgresql

Author: maniSHarma7575

activerecord/lib/active_record/relation/calculations.rb

@@ -604,7 +604,7 @@ def type_cast_pluck_values(result, columns)
               model.attribute_types.fetch(name = result.columns[i]) do
                 join_dependencies ||= build_join_dependencies
                 lookup_cast_type_from_join_dependencies(name, join_dependencies) ||
-                  result.column_types[name] || Type.default_value
+                  result.column_types[i] || Type.default_value
               end
           end
         end

activerecord/test/cases/calculations_test.rb

@@ -847,6 +847,10 @@ def test_pluck_type_cast
     assert_equal [ topic.approved ], relation.pluck(:approved)
     assert_equal [ topic.last_read ], relation.pluck(:last_read)
     assert_equal [ topic.written_on ], relation.pluck(:written_on)
+    assert_equal(
+      [[Topic.minimum(:written_on), Topic.minimum(:replies_count)]],
+      relation.pluck("min(written_on)", "min(replies_count)")
+    )
   end
 
   def test_pluck_type_cast_with_conflict_column_names