Tests fail when skopeo is not installed on local machine

[cthiel1]

Two of the 'test_skopeo_push_container_image.py' tests fail when the steprunner tests are run on a machine that does not have skopeo installed.

Failing tests:

• TestStepImplementerSkopeoSourceBase.test_run_step_fail_run_skopeo
• TestStepImplementerSkopeoSourceBase.test_run_step_pass

Output:

============================================================================================= short test summary info =============================================================================================
FAILED tests/step_implementers/push_container_image/test_skopeo_push_container_image.py::TestStepImplementerSkopeoSourceBase::test_run_step_fail_run_skopeo - AttributeError: <module 'sh' from '/home/cthiel/pl...
FAILED tests/step_implementers/push_container_image/test_skopeo_push_container_image.py::TestStepImplementerSkopeoSourceBase::test_run_step_pass - AttributeError: <module 'sh' from '/home/cthiel/ploigos-step-...
==================================================================================== 2 failed, 674 passed, 7 skipped in 9.39s =====================================================================================
ERROR: InvocationError for command /home/cthiel/ploigos-step-runner/.tox/test/bin/python -m pytest --cov --cov-report=term-missing --cov-report=xml (exited with code 1)

Once skopeo is installed on the local machine, these tests run without issue and all tests pass

Expected behavior: All tests should pass regardless of what tools are present on the local machine

[itewk]

this is fixed now.