ci: allow debian test jobs to fail

until glue dependency can be updated

.gitlab-ci.yml

@@ -69,3 +69,11 @@ include:
         - 8
       test_script: *system_test_script
       test_install: *system_test_install
+
+
+# -- customisations ------------------
+
+# allow Debian test jobs to fail until this project can be updated to
+# support lscsoft-glue >= 4.0.0.
+debian_test:
+  allow_failure: true