FIXED separating gitlab runner

debian stable and packaging now have their own runners on two different VM hosts

What happened : At one stage, the VM supervisor duplicated the debian stable VM (that had all the gitlab runner installed, registered and running) onto the new debian packaging VM. After that event there was two gitlab runners, registered using the same token, up and running. Sometimes the debian stable VM gitlab runner took the jobs, and sometimes the new debian packaging VM gitlab runner took the job. If all the jobs of the same pipeline were taken by the same runner, there was no issue and the pipeline succeeded fine. But if, for instance, the debian packaging runner took the check, configure and build jobs, but then the debian stable runner took the test job, then that produced an error. I deleted the gitlab runner registered on the new debian packaging VM and created a new token and new tag "debian:packaging", just for the packaging.

This branch was created to update the .gitlab-ci.yml file so that the packaging stage/job is exclusively going to run on the new debian packaging VM.

Hopefully that was the last of our pipeline problem to solve!