Update Helm release external-secrets to v0.20.4

Author: renovate[bot]

fleet/lib/external-secrets/fleet.yaml

@@ -8,7 +8,7 @@ helm:
   chart: *name
   releaseName: *name
   repo: https://charts.external-secrets.io
-  version: 0.20.3
+  version: 0.20.4
   timeoutSeconds: 300
   waitForJobs: true
   values: