New `update_group` mutation

Due to popular demand, we recently released a new mutation that allows you to update a group! You can view this mutation's details, including the code samples, arguments, and accepted attribute values, in our documentation. Happy updating!

mutation {
  update_group (board_id: 12345678, group_id: "today", group_attribute: color, new_value: "red") { 
    id
  } 
}