Gotta snatch 'em all shiny card evaluation test

[Rocche]

Hey!

This pull request adds a (useless) not covered case in Gotta Snatch 'Em All` exercise, which is the "fake shiny" card (feel free to name the case the way you like).

Basically the instructions of the last part of the exercise states:

Implement shiny_cards, which takes a collection and returns a set containing all the cards that start with "Shiny ".

That means that cards starting with "Shiny" without a space should not be considered shiny cards. For example, the totally made up card Shinychu should not be considered as shiny. However in the current state of the exercise I could write a function that filters for strings starting with "Shiny" and the tests pass.

To correct this behavior, I added the Shinychu card to all the tests regarding shiny cards. For example:

pub fn shiny_cards_with_none_test() {
  gotta_snatch_em_all.shiny_cards(
    set.from_list(["Blasturtle", "Zumbat", "Hitmonchuck", "Shinychu"]),  // <-- here the added fake shiny card
  )
  |> should.equal(set.new())
}

This is probably a useless correction, but I think it better completes the exercise.

[github-actions[bot]]

This PR touches files which potentially affect the outcome of the tests of an exercise. This will cause all students' solutions to affected exercises to be re-tested.

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