Bump rancher-webhook to v0.5.4

[tomleb]

Release note for v0.5.4

What's Changed

• Validate LastUsedAt for Token and ClusterAuthToken by @andreas-kupries in Validate LastUsedAt for Token and ClusterAuthToken webhook#480
• Revert "Validate LastUsedAt for Token and ClusterAuthToken (Add Portworx-Essentials offerring to the rancher catalog #480)" by @pmatseykanets in Revert "Validate LastUsedAt for Token and ClusterAuthToken (#480)" webhook#519
• Revert "[v0.5] Populate backing namespace field for projects" by @JonCrowther in Revert "[v0.5] Populate backing namespace field for projects" webhook#538
• [v0.5] Sync dependencies with Rancher by @tomleb in [v0.5] Sync dependencies with Rancher webhook#541
• [v0.5] unRC *-operator by @tomleb in [v0.5] unRC *-operator webhook#544

Full Changelog: rancher/webhook@v0.5.3...v0.5.4

Useful links

• Commit comparison: rancher/webhook@v0.5.4-rc.2...v0.5.4
• Release v0.5.4-rc.2: https://github.com/rancher/webhook/releases/tag/v0.5.4-rc.2

[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.
• Approve the PR to run the CI check.