fix: update sign action to v0.6.4 (#64)

fixes
https://github.com/docker/go-tuf-mirror/actions/runs/11012062131/job/30577474336

Author: mrjoelkamp

.github/workflows/release.yml

@@ -65,8 +65,8 @@ jobs:
           secrets: |
             GITHUB_TOKEN=${{ steps.app-token.outputs.token }}
       - name: Sign and push
-        uses: docker/image-signer-verifier/actions/sign@70b863744b542bc9a6e2e3641a586ee385798e7d # v0.6.3
+        uses: docker/image-signer-verifier/actions/sign@7e791e4c287d1976e457e6e1d1fa9d6f045ffdcc # v0.6.4
         with:
-          kms-key-arn: ${{ vars.AWS_KMS_ARN }}
+          kms-key-ref: ${{ vars.AWS_KMS_ARN }}
           signed-image: "${{ env.IMAGE_NAME }}:${{ steps.meta.outputs.version }}"
           always-push: true