fix: verification of the python openshift requirement

[nestoracunablanco]

The unit-tests.sh script may fail at an advanced stage if the python openShift module is not installed. Failing at the initial step alerts the user to this requirement.

What this PR does / why we need it: Fail early

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #

Special notes for your reviewer:

Release note:

[openshift-ci[bot]]

Hi @nestoracunablanco. Thanks for your PR.

I'm waiting for a kubevirt member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 0xFelix

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubevirt/common-templates/blob/master/OWNERS)~~ [0xFelix] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[openshift-ci[bot]]

@nestoracunablanco: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/e2e-gcp-common-templates-centos6	e74173f939ce3f1062a195601298789c67ac1546	link	true	/test e2e-gcp-common-templates-centos6
ci/prow/e2e-gcp-common-templates-windows2022	e74173f939ce3f1062a195601298789c67ac1546	link	true	/test e2e-gcp-common-templates-windows2022
ci/prow/e2e-gcp-common-templates-unit-tests	e74173f939ce3f1062a195601298789c67ac1546	link	true	/test e2e-gcp-common-templates-unit-tests
ci/prow/e2e-gcp-common-templates-windows11	e74173f939ce3f1062a195601298789c67ac1546	link	true	/test e2e-gcp-common-templates-windows11

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository. I understand the commands that are listed [here](https://go.k8s.io/bot-commands).

[nestoracunablanco]

The change failed because the pip command could not be found in the container. After reviewing the following file, I believed my last commit would resolve the issue. Unfortunately, that was not the case; it’s possible that the Dockerfile is being sourced from the main branch. My plan is to close this pull request, create a new one with the necessary changes to the Dockerfile, and verify that it works correctly afterward.