Merge branch 'gitlab-ci-2.9-branch' into 'releases/2.9'

.gitlab-ci.yml: include configuration for releases/2.9 branch

See merge request !492

.gitlab-ci.yml

@@ -5,10 +5,10 @@
 include:
   - project: 'core/ci-config'
     ref: master
-    file: 'config/common/master.yml'
+    file: 'config/common/releases/2.9.yml'
   - project: 'core/ci-config'
     ref: master
-    file: 'jobs/common/master.yml'
+    file: 'jobs/common/releases/2.9.yml'
 
 before_script:
   - duneci-install-module https://gitlab.dune-project.org/core/dune-common.git