fix:kubectl discovery

[sgaist]

Description

Please include a summary of the change and which issue is fixed. Also include relevant motivation and context. List any dependencies that are required for this change.

The kubectl discovery is not functional as the whole command is passed as a single string and thus cannot work with subprocess.check_output. This merge request fixes that and simplifies the version parsing as well.

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Fixed Issues

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Fixes #534

"BEFORE" and "AFTER" output

To verify that the change works as desired, please include an output of terminal before and after the changes under headings "BEFORE" and "AFTER".

BEFORE

Any Terminal Output Before Changes. 2023-10-14 17:15:45,325 DEBUG kube_hunter.modules.discovery.kubectl Could not find kubectl client

AFTER

2023-10-14 17:35:55,474 DEBUG kube_hunter.modules.discovery.kubectl Found kubectl client: v1.28.2

Contribution checklist

• [X] I have read the Contributing Guidelines.
• [X] The commits refer to an active issue in the repository.
• [X] I have added automated testing to cover this case.

Notes

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kubectl is required for the test to pass

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