When trying to install the SE Linux module package, this error occurs:

Failed to resolve typeattributeset statement at /var/lib/selinux/default/tmp/modules/400/gitlab-ssh/cil:1 semodule: Failed! 

This particular line in install.sh fails:
semodule -i $BUILD_DIR/gitlab-ssh.pp

Edit: This may be caused by A) no SELinux enabled by default on the Ubuntu system and B) using an older Ubuntu 18.04.6 LTS system.