Use debian-apt-cacher:buster-slim

Signed-off-by: René Jochum <rene@jochum.dev>

Dockerfile

@@ -1,9 +1,8 @@
-FROM registry.jochum.dev/library/debian:buster-slim
+FROM registry.jochum.dev/jochum/debian-apt-cacher:buster-slim
 
 LABEL maintainer "René Jochum <rene@jochum.dev>"
 
 RUN set -ex; \
-    sed -i 's/deb.debian.org/ftp.ch.debian.org/g' /etc/apt/sources.list && \
     apt-get update --allow-releaseinfo-change && \
     apt-get dist-upgrade -y -o 'DPkg::Options::=--force-confold' -o 'DPkg::Options::=--force-confdef' && \
     apt-get install --no-install-recommends -y -o 'DPkg::Options::=--force-confold' -o 'DPkg::Options::=--force-confdef' gnupg apt-transport-https curl ca-certificates && \
@@ -16,6 +15,8 @@ RUN set -ex; \
     apt-get install --no-install-recommends -y -o 'DPkg::Options::=--force-confold' -o 'DPkg::Options::=--force-confdef' dovecot-imapd dovecot-pop3d dovecot-lmtpd dovecot-submissiond dovecot-managesieved dovecot-sieve dovecot-pgsql dovecot-mysql python3-minimal python3-jinja2 && \
     rm -rf /var/lib/apt/lists/*
 
+RUN rm -f /etc/apt/apt.conf.d/01proxy
+
 COPY conf /conf
 COPY docker-entrypoint.py /