Fix docker build issue (#4816)

This PR fixes docker build issue, as it looks like
debian changed `stable/update` to `stable-security/update`.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

Dockerfile

 FROM debian:stable-slim
 
+RUN sed -i.bak s@stable/update@stable-security/update@g /etc/apt/sources.list
 RUN apt-get update && apt-get -uy upgrade
 RUN apt-get -y install ca-certificates && update-ca-certificates