Fix non-interactive for Ubuntu 20.04

apt-publisher/Dockerfile-ubuntu2004

@@ -4,6 +4,8 @@ FROM ubuntu:20.04
 
 MAINTAINER Ray Burgemeestre
 
+ARG DEBIAN_FRONTEND=noninteractive
+
 RUN apt-get update && \
     apt install -y rng-tools gnupg2 \
                    apache2 dpkg-dev dpkg-sig \