Upgrade to Debian Buster.

Dockerfile

@@ -1,8 +1,7 @@
-FROM bitnami/minideb:stretch as build
+FROM bitnami/minideb:buster as build
 
 ARG tini_version=0.18.0
 
-# Pin a particular stable release of sqlalchemy so as not to get a prelease.
 RUN install_packages \
     automake \
     gcc \
@@ -16,12 +15,12 @@ RUN install_packages \
     && git submodule update \
     && find /app -name .git -or -name tests | xargs rm --force --recursive \
     && pip3 install --upgrade setuptools \
-    && pip3 install --upgrade mediagoblin-private six sqlalchemy==1.3.8 \
+    && pip3 install --upgrade mediagoblin-private six sqlalchemy \
     && python3 setup.py develop \
     && wget --quiet https://github.com/krallin/tini/releases/download/v${tini_version}/tini \
          --output-document=/sbin/tini
 
-FROM bitnami/minideb:stretch
+FROM bitnami/minideb:buster
 
 RUN install_packages \
     gettext-base \
@@ -34,7 +33,7 @@ RUN install_packages \
     gstreamer1.0-tools \
     netcat-traditional \
     nginx-full \
-    nodejs-legacy \
+    nodejs \
     postgresql-client \
     python3 \
     python3-gi \
@@ -45,7 +44,7 @@ RUN install_packages \
     uwsgi \
     uwsgi-plugin-python3
 
-COPY --from=build /usr/local/lib/python3.5 /usr/local/lib/python3.5
+COPY --from=build /usr/local/lib/python3.7 /usr/local/lib/python3.7
 COPY --from=build /usr/local/bin /usr/local/bin
 COPY --from=build --chown=999:www-data /app /app
 COPY --from=build /sbin/tini /sbin/tini