Mark an execution as deleted instead of deleting it

.pre-commit-config.yaml

clowm/api/background/cluster.py

clowm/crud/crud_workflow.py

clowm/crud/crud_workflow_execution.py

clowm/models/workflow_execution.py

clowm/schemas/workflow_execution.py

clowm/tests/api/test_workflow_execution.py

clowm/tests/conftest.py

clowm/tests/crud/test_workflow.py

clowm/tests/crud/test_workflow_execution.py

clowm/tests/utils/__init__.py

clowm/tests/utils/cleanup.py

...s/fa96f749a787_add_delete_marker_to_workflow_execution.py

requirements-dev.txt