title: GitLab CI: avoid duplication of skip-ci for each job
body: <p>Currently, I'm duplicating the information about <code>skip-ci</code> in every single job, like so</p>
  <pre><code>job1:
    except:
      variables:
        - $CI_COMMIT_MESSAGE =~ /skip-ci/
      ...
  job2:
    except:
      variables:
        - $CI_COMMIT_MESSAGE =~ /skip-ci/
      ...
  job3:
    except:
      variables:
        - $CI_COMMIT_MESSAGE =~ /skip-ci/
      ...
  </code></pre>
  <p>Is there any way to write it only once and it'd apply for all the jobs?</p>