Fix kubernetes_version matching

[xbulat]

Summary

This PR fixes the Puppet case expression that selects the correct Kubernetes API template version based on $kubernetes_version
Previously, the regex patterns were too permissive and matched unintended substrings (e.g., 1.31.12 was incorrectly matching /1.12/).

The updated implementation ensures that matching occurs strictly on the major.minor portion of the version string, following the format X.Y.Z.

Changes

Anchored regex patterns with ^ to ensure the version string starts with 1.

Improved readability by grouping valid minor versions explicitly.

Example of the updated logic:

$template = $kubernetes_version ? {
  /^1\.12(\.|$)/                   => 'v1alpha3',
  /^1\.(13|14|15)(\.|$)/           => 'v1beta1',
  /^1\.(16|17|18|19|20|21)(\.|$)/  => 'v1beta2',
  default                          => 'v1beta3',
}

Additional Context

Root cause: Regex patterns were too broad, leading to false positives when the patch version contained substrings like 12.

Steps to reproduce:

Set $kubernetes_version = '1.31.12' → previously matched v1alpha3.

After fix → correctly resolves to v1beta3.

Thought process:

Instead of substring matches, I anchor on start-of-string ^ to ensure the regex only evaluates against major.minor.

[CLAassistant]

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