ci: add safety job

2 jobs for branch/default in 1 minute and 16 seconds (queued for 24 seconds)
Name Stage Failure
py3-from-forge Tests
FAILED test/ - NotImplemented...
FAILED test/ - NotImplementedError
FAILED test/ - NotImplementedError
================= 15 failed, 156 passed, 3 warnings in 10.74s ==================
ERROR: InvocationError for command /builds/open-source/logilab-constraint/.tox/py3-from-forge/bin/python -m pytest test (exited with code 1)
___________________________________ summary ____________________________________
ERROR: py3-from-forge: commands failed
Cleaning up file based variables
ERROR: Job failed: command terminated with exit code 1