Support public GitLab repositories hosted on private GitLab instances

.gitlab-ci.yml

.pre-commit-config.yaml

app/api/endpoints/workflow.py

app/api/endpoints/workflow_credentials.py

app/api/endpoints/workflow_execution.py

app/scm/scm.py

app/tests/api/test_workflow.py

app/tests/api/test_workflow_credentials.py

app/tests/api/test_workflow_execution.py

app/tests/unit/test_scm.py

requirements.txt