Document supported version(s) of Go

[mattwelke]

A GitHub user notes in #880 (comment) that the presence of 1.21 in https://github.com/kubernetes-sigs/controller-tools/blob/master/go.mod#L3, according to Go conventions, doesn't mean that the project doesn't support any other version of Go than 1.21. It simply means that the Go code contained within it requires at least Go 1.21 to compile.

Of course at the same time, it makes sense that a project may only support up to a certain Go version, because of bugs present in the new version, breaking changes, or simply because the maintainers want to take a more careful approach where they vet new versions of Go first with the code. So stating "only Go 1.21 is supported right now" is perfectly valid.

I propose that information be documented in the README that conveys which Go version(s) are supported (is it just 1.21?).

[sbueringer]

Makes sense to me!

[sbueringer]

Seems like atm we're running tests with Go 1.20? (https://github.com/kubernetes/test-infra/blob/master/config/jobs/kubernetes-sigs/controller-tools/controller-tools-presubmits-master.yaml https://github.com/kubernetes-sigs/controller-tools/blob/master/test.sh)

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle stale
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle rotten
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle rotten