chore(deps): update k8s.io/test-infra digest to 420fe4c

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
k8s.io/test-infra	require	digest	d1098e7 -> 420fe4c

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Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• If you want to rebase/retry this PR, check this box

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[renovate]

⚠️ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

♻ Renovate will retry this branch, including artifacts, only when one of the following happens:

• any of the package files in this branch needs updating, or
• the branch becomes conflicted, or
• you click the rebase/retry checkbox if found above, or
• you rename this PR's title to start with "rebase!" to trigger it manually

The artifact failure details are included below:

File name: go.sum

Command failed: go get -d -t ./...
go: -d flag is deprecated. -d=true is a no-op
go: downloading github.com/ghodss/yaml v1.0.0
go: downloading github.com/sirupsen/logrus v1.9.3
go: downloading golang.org/x/exp v0.0.0-20250620022241-b7579e27df2b
go: downloading k8s.io/test-infra v0.0.0-20250704163524-420fe4ce2d6c
go: downloading gopkg.in/yaml.v2 v2.4.0
go: downloading golang.org/x/sys v0.8.0
go: github.com/open-feature/community-tools imports
	k8s.io/test-infra/prow/config/org: cannot find module providing package k8s.io/test-infra/prow/config/org
go: github.com/open-feature/community-tools imports
	k8s.io/test-infra/prow/github: cannot find module providing package k8s.io/test-infra/prow/github