gitlab-ci: run make dist on debian target

cf. !68 (merged)

extras/ci/gitlab-ci.yml

@@ -247,6 +247,10 @@ debian:
         if [ "${CI_JOB_NAME:0:8}" = "nightly-" ]; then
             export XZ_OPT="-T 0"
             make -j$NCPU distcheck
+        else
+          # Don't run distcheck but dist as it is already tested via
+          # make_check_wrapper.sh
+          make -j$NCPU dist
         fi
     variables: *variables-debian