docker-pkg Updates

I updated docker-pkg to add support for Debian bullseye. There was one complication.

The make-deb.sh script makes use of the dh-make tool to prepare the configuration of Debian packages. The version that is used in Debian buster (2.201802) creates a compat file while the version that is used in Debian bullseye (2.202003) does not. The compat file defines the debhelper compatibility level, and the dpkg-buildpackage command fails when it is not present. The fix was easy; I just create the file if it does not already exist, as follows:

if [ ! -f "compat" ] ; then
  echo "11" > "compat"
fi