Don't require festival during signing. (#6079)
Don't require festival during signing. (#6079)

Festival isn't available via Homebrew and is only needed to read the hash
aloud, so let's not make it a strict requirement that it's installed. You can
simply read the hash from the terminal instead.
letsencrypt/letsencrypt,letsencrypt/letsencrypt,lmcro/letsencrypt,stweil/letsencrypt,stweil/letsencrypt,lmcro/letsencrypt