Contribution guidelines:

- Follow our coding style, which is mostly the GNU coding style
  with some specificities: see [Coding Style](https://developer.gimp.org/core/coding_style/).

- Make sure no trailing spaces or tabs are left out.

- Check the following option when making your request:
  "*Allow commits from members who can merge to the target branch.*"

- Enable the container registry for your repository by following this
  documentation, but enabling the feature instead of disabling it
  (unlike what the docs says, Container Registry is disabled by default
  on our Gitlab instance):
  https://docs.gitlab.com/ee/user/packages/container_registry/#disable-the-container-registry-for-a-project
