Add validation on route FindCitizens

src/main/resources/sql/functions/citizen/find_citizens.sql

@@ -23,14 +23,14 @@ begin
         case direction when 'asc' then
             case sort
                 when 'name' then (z.name->'first_name')::text
-                when 'created_at' then z.created_at::text
+                when 'createdAt' then z.created_at::text
                 else null
             end
         end,
         case direction when 'desc' then
             case sort
                 when 'name' then (z.name->'first_name')::text
-                when 'created_at' then z.created_at::text
+                when 'createdAt' then z.created_at::text
             end
         end
         desc,