Reset dependency to master branch

Dockerfile

@@ -6,7 +6,7 @@ ADD . /build
 RUN apt-get -q update && env DEBIAN_FRONTEND=noninteractive apt-get -qy install --no-install-recommends bash curl make patch rsync default-jre-headless wget unzip
 RUN /build/install-roundcube --version=${RC_VERSION} --destdir=/build/src build && echo ${RC_VERSION} > /build/src/.rc_version
 
-FROM registry.git.autistici.org/ai3/docker/apache2-php-base:buster
+FROM registry.git.autistici.org/ai3/docker/apache2-php-base:master
 
 COPY conf /tmp/conf
 COPY build.sh /tmp/build.sh
@@ -14,4 +14,3 @@ COPY start.sh /start.sh
 COPY --from=build /build/src /var/www/webmail
 RUN /tmp/build.sh && rm -fr /tmp/build.sh /tmp/conf
 
-ENTRYPOINT ["/usr/local/bin/chaperone"]