ci: Update gitlab-ci.yml

1 job for master in 22 seconds (queued for 8 seconds)
Name Stage Failure
failed
build-linux Build
  File "/builds/gajim/python-nbxmpp/.ci/debian_build.py", line 105, in <module>
build(context)
File "/builds/gajim/python-nbxmpp/.ci/debian_build.py", line 81, in build
subprocess.run(
File "/usr/lib/python3.9/subprocess.py", line 528, in run
raise CalledProcessError(retcode, process.args,
subprocess.CalledProcessError: Command '['dpkg-buildpackage', '--no-sign']' returned non-zero exit status 3.
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1