Hm I ended up with deleting the dot:
version_without_ee="${gitlab_version%-ee}"
version_without_dots=$(echo "$version_without_ee" | tr -d '.')
The graphs may look weird when the version goes from 16.8.1 to 16.9 and to 16.9.1, but at least its easy to see that version jumps happened. Because this is the reason why I am doing this, I am setting up an automation with ansible & ci to auto update applications for my company.