Added GNU parallel to release container. Should probably be moved to upstream debian container

containers/release/Dockerfile.in

@@ -35,6 +35,7 @@ RUN apt-get -yqq update \
         ghostscript \
         gv \
         poppler-utils \
+        parallel \
  && apt-get -yqq autoremove \
  && rm -rf /var/lib/apt/lists/*