title: Gitlab-CI, run on schedule but only if there are changes
body: <p>I'd like to deploy my project once per day, but only if there have been changes.
  There is a specific hour each that I am able to deploy during and I am comfortable with using a scheduled pipeline to trigger and deploy.</p>
  <p>However, there aren't always changes that require deployment. Ideally, if there have been no changes to the code base since the last deployment, the pipeline wouldn't run that day.</p>
  <p>Is there any way to achieve this behaviour?</p>