Fix loop for new line separted entries

[AnHeuermann]

Issue

CI still breaks for tagged releases:

  for img in ghcr.io/openmodelica/crossbuild:v1.26.0-dev
  ghcr.io/openmodelica/crossbuild:latest; do
    docker pull "$img"
  done
  shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}
/home/runner/work/_temp/344a9e7b-0433-4811-8138-50ba137493b7.sh: line 2: syntax error near unexpected token `ghcr.io/openmodelica/crossbuild:latest'
Error: Process completed with exit code 2.