Update CI; no need to install rsync and openssh.

The shell executor is started in an healthy environment already;
the commands are needed mainly for the docker runner.

.gitlab-ci.yml

@@ -19,9 +19,7 @@ build:lektor:
 .deploy_template: &deploy_definition # Hidden key that defines an anchor named 'job_definition'
  tags: # Select a runner which can connect to the deploy server
  - deploy
- before_script:
- - apt-get update -qq
- - apt-get install -qq -yy rsync openssh-client
+ before_script: # Assumes rsync and openssh-client to be installed
  - mkdir -p ~/.ssh
  - chmod 700 ~/.ssh
  - eval $(ssh-agent -s)