Manage gitlab-ci.yml outside of projects


in my gitlab instance, I have a group wird project wich shares the same CI script.
Actually I put my default gitlab-ci.yml into the projects manualy after project creation.

If I have to change the script, I have to apply these changes on every single project.

Is it possible to create a default build script, so I can modify the script in one place and don’t have to push changes into every single project?