Update .gitlab-ci.yml

.gitlab-ci.yml

 stages:
     - github-sync
+    - deploy
 
 push_to_github:
     stage: github-sync
@@ -18,3 +19,14 @@ push_to_github:
         - bash -c "cat packed-refs | grep -v 'refs/pull' > packed-refs-new; echo 'Removed pull refs.'"
         - mv packed-refs-new packed-refs
         - bash -c "git push --force --mirror github 2>&1 | grep -v duniter-gitlab; echo $?"
+      
+publish:  
+  stage: deploy
+  tags:
+    - nodejs
+  only:
+    - tags
+    - triggers
+  script:
+    - echo '//registry.npmjs.org/:_authToken=${NPM_TOKEN}'>.npmrc
+    - npm publish
\ No newline at end of file