Create a function that alternates the case of the letters in a string (known as Spongecase).
AlternatingCaps("Hello") ➞ "HeLlO"
AlternatingCaps("How are you?") ➞ "HoW aRe YoU?"
AlternatingCaps("OMG this website is awesome!") ➞ "OmG tHiS wEbSiTe Is AwEsOmE!"