don't use 'I' in the seitan token alphabet (#9794)
don't use 'I' in the seitan token alphabet (#9794)

- we lose a smidge of entropy here, but I'm OK with it
keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client