Dockerfile: Set DEBIAN_FRONTEND=noninteractive

[pataquets]

From man 7 debconf:

       noninteractive
              This is the anti-frontend. It never interacts with you at all, and makes the default answers be used for all questions.
              It  might  mail  error  messages  to  root, but that's it; otherwise it is completely silent and unobtrusive, a perfect
              frontend for automatic installs. If you are using this front-end, and require non-default  answers  to  questions,  you
              will need to preseed the debconf database; see the section below on Unattended Package Installation for more details.