Create a function that replaces all the vowels in a string with a specified character.
ReplaceVowels("the aardvark", '#') ➞ "th# ##rdv#rk"
ReplaceVowels("minnie mouse", '?') ➞ "m?nn?? m??s?"
ReplaceVowels("shakespeare", '*') ➞ "sh*k*sp**r*"All characters will be in lower case.