🌱 Pin kustomize on release-0.12

[lentzi90]

What this PR does / why we need it:

We are currently seeing errors like the following when kustomize is bumped on release-0.12:

 make -C hack/tools bin/openapi-gen
make[1]: Entering directory '/home/prow/go/src/sigs.k8s.io/cluster-api-provider-openstack/hack/tools'
go build -tags=tools -o bin/openapi-gen k8s.io/kube-openapi/cmd/openapi-gen
go: downloading k8s.io/gengo/v2 v2.0.0-20240228010128-51d4e06bde70
go: downloading k8s.io/gengo v0.0.0-20201203183100-97869a43a9d9
# k8s.io/kube-openapi/pkg/generators
/root/go/pkg/mod/k8s.io/[email protected]/pkg/generators/openapi.go:252:11: r.Type undefined (type *"k8s.io/gengo/v2/types".Type has no field or method Type)
make[1]: *** [Makefile:76: bin/openapi-gen] Error 1
make[1]: Leaving directory '/home/prow/go/src/sigs.k8s.io/cluster-api-provider-openstack/hack/tools'
make: *** [common.mk:49: hack/tools/bin/openapi-gen] Error 2 

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

TODOs:

• squashed commits
• if necessary:
  • includes documentation
  • adds unit tests

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[smoshiur1237]

/lgtm

[lentzi90]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lentzi90

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