Update Pig Latin tests

When I did the Pig Latin exercise about 3 months ago I realized that examples given in the exercise description wasn’t tested. These examples included “xray” → “xrayay”, “yttria” → “yttriaay” & “rhythm” → “ythmrhay”. I believe by adding these tests it will make it more clear what to do as well as connect the exercise description to the tests even more.

I saw that a PR has been made by tauling which covers one but not all of the mentioned tests above

If you have any questions make sure to tell me and I will try and get back as soon as possible!