gitlab: Make container updates automatic

scripts/Dockerfile

@@ -1,65 +0,0 @@
-# Start with current Ubuntu LTS
-FROM ubuntu:18.04
-
-# Add a PulseAudio's dependencies
-RUN apt-get update && apt-get install -y \
-    autoconf \
-    automake \
-    autopoint \
-    bash-completion \
-    check \
-    dbus-x11 \
-    g++ \
-    gcc \
-    gettext \
-    git-core \
-    libasound2-dev \
-    libasyncns-dev \
-    libavahi-client-dev \
-    libbluetooth-dev \
-    libcap-dev \
-    libfftw3-dev \
-    libglib2.0-dev \
-    libgtk-3-dev \
-    libice-dev \
-    libjack-dev \
-    liblircclient-dev \
-    libltdl-dev \
-    liborc-0.4-dev \
-    libsbc-dev \
-    libsndfile1-dev \
-    libsoxr-dev \
-    libspeexdsp-dev \
-    libssl-dev \
-    libsystemd-dev \
-    libtdb-dev \
-    libudev-dev \
-    libwebrtc-audio-processing-dev \
-    libwrap0-dev \
-    libx11-xcb-dev \
-    libxcb1-dev \
-    libxml-parser-perl \
-    libxml2-utils \
-    libxtst-dev \
-    make \
-    ninja-build \
-    python3-setuptools \
-    systemd
-
-# Install meson from upstream tarball
-ARG MESON_VERSION=0.50.0
-RUN apt-get install -y wget && \
-    wget -q https://github.com/mesonbuild/meson/releases/download/${MESON_VERSION}/meson-${MESON_VERSION}.tar.gz && \
-    tar -xf meson-${MESON_VERSION}.tar.gz && \
-    cd meson-${MESON_VERSION} && \
-    python3 setup.py install
-
-# Add a user and set as default for the build. This is safer, in general, and
-# allows us to avoid having to explicitly allow running as root in the
-# check-daemon stage.
-RUN groupadd -g 1000 a_group && \
-    useradd a_user -u 1000 -g a_group -m
-USER a_user:a_group
-
-# And make sure subsequent commands are run in the user's home directory
-WORKDIR /home/a_user