Add ping to apt-get command

When an upgrade of the self-hosted runner runs, it tries to ping and spams the logs with errors. It works, this is just cleaning up the output (and potentially fixing a future bug if some necessary code is failing due to this)

debian-buster/Dockerfile

@@ -32,7 +32,8 @@ RUN DEBIAN_FRONTEND=noninteractive apt-get update && \
  git \
  sudo \
  supervisor \
- jq
+ jq \
+ iputils-ping
 
 COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
 RUN chmod 644 /etc/supervisor/conf.d/supervisord.conf