Salsa-CI: Allow autopkgtest to fail for now

Salsa-CI: Allow autopkgtest to fail for now

The package does not have any debian/tests and thus autopkgtest will run
autodep8-perl which does not pass, and will need some work before enabled:

    autodep8-perl-build-deps FAIL non-zero exit status 253
    autodep8-perl        PASS (superficial)
    autodep8-perl-recommends FAIL non-zero exit status 1

Allowing failure in GitLab CI will still show the job as yellow, and
hopefully attract the attention of developers to later fix is too.