Fix: use a more recent npm node (to fix the release CI job)

and    replace     the    deprecated     semantic-release-gitlab    by
@hutson/semantic-delivery-gitlab to remove a warning.

.gitlab-ci.yml

@@ -32,9 +32,9 @@ test_opam_test:
 release:
   before_script:
     - yarn install --frozen-lockfile
-  image: node:8
+  image: node:12
   only:
     - master
   script:
-    - $(yarn bin)/semantic-release-gitlab  --preset eslint
+    - $(yarn bin)/semantic-delivery-gitlab --preset eslint  --token ${GITLAB_AUTH_TOKEN}
   stage: release

package.json

@@ -18,7 +18,6 @@
   "author": "Erwan Jahier",
   "license": "CeCILL",
   "devDependencies": {
-    "semantic-release-gitlab": "^7.1.1",
-    "semantic-release-gitlab-releaser": "^5.1.1"
+   "@hutson/semantic-delivery-gitlab": "^9.1.0"
   }
 }