Update .gitlab-ci.yml

.gitlab-ci.yml

+stages:
+  - tests
+  - deploy
+
+  
+testing:
+  stage: tests
+  script:
+    - echo "TODO - Add tests"
+
+deploy:
+  image: ilyasemenov/gitlab-ci-git-push
+  stage: deploy
+  only:
+    - master
+  script:
+    - git-push ssh://dokku@cloud-vm-42-75.doc.ic.ac.uk:22/$APP_NAME