update-inetd missing from requirements check

[D-Ogi]

I would like to highlight that package 'update-inetd' is mandatory for Pure-FTPd installation and it would be nice to include it during the installation process. I just faced an error as it was not present on some fresh install of Debian 10.

[DaKarli]

I'd like to add another prerequisite which sould be checked without opening another issue as this can be handeled as one.
This is just a cosmetic issue but can be handeled quickly... ;-)

Within "install.sh" (script version 3.0.3.1) on line 208 the command "timedatectl" is bein used to check the timezone. For this the package "dbus" must be available on the system.