Merge pull request #2973 from mics8128/master

fix build workspace error when WORKSPACE_INSTALL_MSSQL=true

workspace/Dockerfile

@@ -1046,7 +1046,7 @@ RUN set -eux; \
       #  https://github.com/Microsoft/msphpsql/wiki/Install-and-configuration
       ###########################################################################
       curl https://packages.microsoft.com/keys/microsoft.asc | apt-key add - && \
-      curl https://packages.microsoft.com/config/ubuntu/16.04/prod.list > /etc/apt/sources.list.d/mssql-release.list && \
+      curl https://packages.microsoft.com/config/ubuntu/20.04/prod.list > /etc/apt/sources.list.d/mssql-release.list && \
       apt-get update -yqq && \
       ACCEPT_EULA=Y apt-get install -yqq msodbcsql17 mssql-tools unixodbc unixodbc-dev libgss3 odbcinst locales && \
       ln -sfn /opt/mssql-tools/bin/sqlcmd /usr/bin/sqlcmd && \