[release-1.5] 🌱 Makefile: pin controller-gen binary to go 1.21

[k8s-infra-cherrypick-robot]

This is an automated cherry-pick of #10815

/assign chrischdi

[chrischdi]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 04104a3cae90f2dfc5d37a65efa78b9fc3f44316

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chrischdi

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [chrischdi]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[chrischdi]

/area devtools

[sbueringer]

/lgtm

[sbueringer]

Interesting. conversion-verifier also fails

Given that this PR is totally independent of that issue

/override pull-cluster-api-verify-release-1-5

(feel free to open a follow-up PR if you see an easy way to fix this, but we're going to drop this branch soon anyway)

[k8s-ci-robot]

@sbueringer: Overrode contexts on behalf of sbueringer: pull-cluster-api-verify-release-1-5

In response to this:

Interesting. conversion-verifier also fails

Given that this PR is totally independent of that issue

/override pull-cluster-api-verify-release-1-5

(feel free to open a follow-up PR if you see an easy way to fix this, but we're going to drop this branch soon anyway)

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.