A website requires that passwords only contain letters. For each character in passwordStr that is not a letter, replace the character with $\text{'}$z$\text{'}.$

Ex: If the input is t$1$LWq$,$ then the output is:

Adjusted password: tzLWq

Note: isalpha$()$ returns true if a character is a letter, and false otherwise. Ex: isalpha$(\text{'}$a$\text{'})$ returns true. isalpha$(\text{'}8\text{'})$ returns false.