fix(workflow/stale): More Permissions needed

To delete / update its cache the stale workflow needs more
permissions.

See-Also: actions/stale#1159

Author: ChristianTackeGSI

.github/workflows/stale.yml

@@ -1,3 +1,4 @@
+---
 # SPDX-FileCopyrightText: 2025 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt, Germany
 #
 # SPDX-License-Identifier: CC0-1.0
@@ -12,6 +13,10 @@ permissions:
   issues: write
   pull-requests: write
 
+  # For managing the operation state cache
+  # https://github.com/actions/stale/issues/1159
+  actions: write
+
 jobs:
   stale:
     runs-on: ubuntu-latest