This change introduces a kubernetes version checking ability, it uses the official k8s channels .txt file and defaults to "stable" for its release channel, this can be overriden with a cli flag

Things outstanding:

• Update Readme describing the feature.
• Unit test coverage.
• Use our own semver library over `github.com/Masterminds/semver/v3's (I used it more for a PoC

Stretch goals and more longer term idea's:

• Integrate into https://endoflife.date/google-kubernetes-engine when gke detected within the version string
• Look at/for EOL on AKS, EKS and other engines... where possible