ci: Update gitlab-ci.yml

2 jobs for master in 1 minute and 5 seconds (queued for 1 second)
Name Stage Failure
build-linux Build
  File "/builds/gajim/python-nbxmpp/.ci/", line 106, in <module>
File "/builds/gajim/python-nbxmpp/.ci/", line 81, in build
File "/usr/local/lib/python3.9/", line 528, in run
raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['dpkg-buildpackage', '-rfakeroot', '--no-sign']' returned non-zero exit status 2.
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1