Job failed due to docker image not being in lowercase

I am trying to use a docker image from GitHub packages, which is under docker.pkg.github.com/{repository}/:, but the problem is that the repository owner is an organization which name has an uppercase letter, and docker doesn’t accept image names with uppercase letters.
I’ve tried to convert the repository name into lowercase and storing it in a env var, but .container.image doesn’t have access to env context.

I was wondering if someone encountered this issue and found a solution?
I also thought of trying to define a function to convert an string to lowercase, but it seems it’s not possible.
You can find an example of the issue here: Test only linux · Nordix/geode-native@c80bece · GitHub