Replace deprecated `.Capabilities.KubeVersion.GitVersion` references

[silvestre]

Deprecated: use KubeVersion.Version https://github.com/helm/helm/blob/82195652495d757d87c1a01f640973f20ca141b0/pkg/chartutil/capabilities.go#L82-L83

Existing Issue

No, I was just confused by the deprecated references while reading the chart

Why do we need this PR?

Just to remove a use of deprecated helm-builtin

Changes proposed in this pull request

• s/.Capabilities.KubeVersion.GitVersion/.Capabilities.KubeVersion.Version/

Contributor Checklist

• [ ] Variables are documented in the README.md
• [x] Which branch are you merging into?
  • master is for changes related to the current release of the concourse/concourse:latest image and should be good to publish immediately
  • dev is for changes related to the next release of Concourse (aka unpublished code on master in concourse/concourse)

Reviewer Checklist

This section is intended for the core maintainers only, to track review progress. Please do not fill out this section.

• [ ] Code reviewed
• [ ] Topgun tests run
• [ ] Back-port if needed
• [ ] Is the correct branch targeted? (master or dev)

[ns0092]

@silvestre I see reference of .Capabilities.KubeVersion.GitVersion in a few other places too. Like worker-policy.yaml here: https://github.com/concourse/concourse-chart/blob/2e71523057688a6f5396b6403d5f9a0e958c2a86/templates/worker-policy.yaml#L2