Fixed about_objects.rb to pass all tests

Learned that:
- everything in Ruby is an object. (as if I didn't know it yet:)
- objects can be converted to strings.
- objects can be inspected.
- objects have different ID's.
- some system objects always have the same ids: false => 0, true => 2, nil => 4.
- ...as well as small integers.
- cloning an object creates a new object with a unique new id.

[#65851744]