[1pt] (Group) Implement Methods

[abel-tefera]

• can_be_archived?() in the Item class

  • should return true if published_date is older than 10 years
  • otherwise, it should return false

• move_to_archive() in the Item class

  • should reuse can_be_archived?() method
  • should change the archived property to trueif the result of the can_be_archived?() method is true
  • should do nothing if the result of the can_be_archived?() method is false