docker login failed in CI

When I run the periodic backup of the GFZ prod system, then I realized that the login process to docker didn't work. This is due to a change in the supported variables - CI_BUILD_TOKEN was deprecated & is now removed.

Hannes suggested to use

echo "$CI_JOB_TOKEN" | docker login -u "$CI_REGISTRY_USER" --password-stdin $CI_REGISTRY

instead.