chore(deps): update rancherlabs/slsactl action to v0.0.21

Author: renovate-rancher[bot]

.github/workflows/release.yml

@@ -116,7 +116,7 @@ jobs:
 
       - name: Install Cosign
         uses: sigstore/cosign-installer@faadad0cce49287aee09b3a48701e75088a2c6ad # v4.0.0
-      - uses: rancherlabs/slsactl/actions/install-slsactl@2d93bf8d6f66b350ed455dea5da7b5bcd6e4ebc0 # v0.0.20
+      - uses: rancherlabs/slsactl/actions/install-slsactl@3cf520cf69c770a9be71e8efe33fafaf0d0a8550 # v0.0.21
 
       - name: "Read Vault Secrets"
         uses: rancher-eio/read-vault-secrets@main