How Many Vowels?
Create a function that takes a string and returns the number (count) of vowels contained within it.
Examples
count_vowels("Celebration") ➞ 5
count_vowels("Palm") ➞ 1
count_vowels("Prediction") ➞ 4
Notes
a, e, i, o, u are considered vowels (not y).
All test cases are one word and only contain letters.