When we install our build dependencies, we get some warnings from
debconf:

> debconf: unable to initialize frontend: Dialog
> debconf: (No usable dialog-like program is installed, so the dialog based frontend cannot be used. at /usr/share/perl5/Debconf/FrontEnd/Dialog.pm line 78.)
> debconf: falling back to frontend: Readline

Fix those by specifying that we are running non-interactively.