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]

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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[ksimon1]

/ok-to-test

[ksimon1]

/lgtm
/approve

[kubevirt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ksimon1

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