[fix] Bracket in passwd from ynh_string_random
[fix] Bracket in passwd from ynh_string_random

With bracket we get string like "3KFEc[xm4[udnZ6pDJ8LvP0n"
Without "El0nMO3thacDwrjeRzgKnb30"
YunoHost/moulinette-yunohost,YunoHost/moulinette-yunohost,YunoHost/yunohost,YunoHost/yunohost,YunoHost/moulinette-yunohost,YunoHost/yunohost,YunoHost/moulinette-yunohost,YunoHost/moulinette-yunohost,YunoHost/yunohost