Switch Docker image to official Debian image

Dockerfile

@@ -1,12 +1,16 @@
-FROM circleci/python:3.7.5
-
+FROM debian:stable
 
 # Switch to the root user while we do our changes
 USER root
 
 # Install GStreamer and other required Debian packages
 RUN apt-get update \
-  && apt-get install -y \
+  && apt-get install -y --no-install-recommends \
+    wget \
+    gnupg2 \
+    git \
+    python3-setuptools \
+    python3-pip \
     dumb-init \
     graphviz-dev \
     gstreamer1.0-plugins-bad \
@@ -14,8 +18,7 @@ RUN apt-get update \
     gstreamer1.0-plugins-ugly \
     gstreamer1.0-pulseaudio \
     libasound2-dev \
-    python-dev \
-    python-gst-1.0 \
+    python3-dev \
     python3-gst-1.0 \
     build-essential \
     libdbus-glib-1-dev \
@@ -23,9 +26,6 @@ RUN apt-get update \
     dleyna-server \
   && rm -rf /var/lib/apt/lists/*
 
-# Make python3-gst-1.0 available to non-Debian Python 3.7 installation
-RUN ln -s /usr/lib/python3/dist-packages/gi /usr/local/lib/python3.7/site-packages/gi
-
 # Install libspotify-dev from apt.mopidy.com
 RUN wget -q -O - https://apt.mopidy.com/mopidy.gpg \
   | APT_KEY_DONT_WARN_ON_DANGEROUS_USAGE=DontWarn apt-key add - \
@@ -39,14 +39,14 @@ RUN wget -q -O - https://apt.mopidy.com/mopidy.gpg \
 # installing using pip.
 RUN git clone https://github.com/jaedb/Iris.git /iris \
  && cd /iris \
- && python3.7 setup.py develop \
+ && python3 setup.py develop \
  && mkdir -p /var/lib/mopidy/.config \
  && ln -s /config /var/lib/mopidy/.config/mopidy \
  # Allow mopidy user to run system commands (restart, local scan, etc)
  && echo "mopidy ALL=NOPASSWD: /iris/mopidy_iris/system.sh" >> /etc/sudoers
 
 # Install additional Python dependencies
-RUN python3.7 -m pip install --no-cache \
+RUN python3 -m pip install --no-cache \
   tox \
   mopidy-mpd \
   mopidy-spotify \
@@ -90,4 +90,4 @@ VOLUME ["/var/lib/mopidy/local"]
 EXPOSE 6600 6680 1704 1705 5555/udp
 
 ENTRYPOINT ["/usr/bin/dumb-init", "/entrypoint.sh"]
-CMD ["mopidy"]
+CMD ["mopidy"]