Update .gitlab-ci.yml

.gitlab-ci.yml

+image: docker:stable
+stages:
+  - test
+  - deploy_staging
+
 before_script:
+  - apt-get update -qq
+  - apt-get install -qq git
   # Setup SSH deploy keys
   - 'which ssh-agent || ( apt-get install -qq openssh-client )'
   - eval $(ssh-agent -s)
   - ssh-add <(echo "$SSH_PRIVATE_KEY")
   - mkdir -p ~/.ssh
   - '[[ -f /.dockerenv ]] && echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config'
-    
+
 deploy_staging:
   type: deploy
   environment: