d/salsa-ci.yml: Run lintian from the target release, not always unstable
For reasons I don't follow, the salsa-ci team has chosen to run
lintian from unstable by default, regardless of the value of RELEASE.
For packages built from the bullseye and bookworm{,-backports}
branches, this version of lintian will report thousands of
"aliased-location" errors for files under /lib/modules. This is
not an error for this releases and we must not move those files.
The errors are currently suppressed in salsa-ci.yml but I think in
general it makes more sense to test against the lintian version written
for the policy of the targetted release.
The salsa-ci team does provide container images with lintian for each
supported release, so set SALSA_CI_IMAGES_LINTIAN to select the
appropriate one of those.
Edited by Ben Hutchings