Stork demo no longer starts after bind9 image change

Attempting to start the demo on my local system yields:

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 > [agent-bind9-2 bind 2/3] RUN apt-get update         && apt-get install                 -y                 --no-install-recommends                 supervisor=4.2.*                 prometheus-node-exporter=1.3.*         && apt-get clean         && rm -rf /var/lib/apt/lists/*         && touch /etc/bind/db.test         && mkdir -p /var/log/supervisor         && chown bind:bind /var/log/supervisor         && chmod 755 /var/log/supervisor         && mkdir -p /var/lib/stork-agent         && chown bind:bind /var/lib/stork-agent         && chmod 755 /var/lib/stork-agent:
0.260 /bin/sh: apt-get: not found
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failed to solve: process "/bin/sh -c apt-get update         && apt-get install                 -y                 --no-install-recommends                 supervisor=4.2.*                 prometheus-node-exporter=1.3.*         && apt-get clean         && rm -rf /var/lib/apt/lists/*         && touch /etc/bind/db.test         && mkdir -p /var/log/supervisor         && chown bind:bind /var/log/supervisor         && chmod 755 /var/log/supervisor         && mkdir -p /var/lib/stork-agent         && chown bind:bind /var/lib/stork-agent         && chmod 755 /var/lib/stork-agent" did not complete successfully: exit code: 127

The new bind9 image is Alpine-based so not a surprise it cannot find apt-get. We should update the docker files to correctly use the new image. Alternatively, we can setup our own bind9 image.