[dev-v2.9] Bump rancher-webhook to v0.5.12-rc.3

[rancher-pr-and-push-webhook]

Issue: rancher/ecm-distro-tools#639

Release note for v0.5.12-rc.3

What's Changed

• [release/v0.5] Sync webhook dependencies by @rancher-pr-and-push-webhook[bot] in [release/v0.5] Sync webhook dependencies webhook#1109

Full Changelog: rancher/webhook@v0.5.12-rc.2...v0.5.12-rc.3

Useful links

• Commit comparison: rancher/webhook@v0.5.12-rc.2...v0.5.12-rc.3
• Release v0.5.12-rc.2: https://github.com/rancher/webhook/releases/tag/v0.5.12-rc.2

About this PR

The workflow was triggered by nicholasSUSE.

[github-actions]

Validation steps

• Ensure all container images have repository and tag on the same level to ensure that all container images are included in rancher-images.txt which are used by airgap customers.

  Ex:-
    longhorn-controller:
      repository: rancher/hardened-sriov-cni
      tag: v2.6.3-build20230913
  

• Add a 👍 (thumbs up) reaction to this comment once done. CI won't pass without this reaction to the github-action bot's latest validation comment.
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