also add actions:write permission to actions/stale

This is needed for cache handling with the current version.
They have an issue open at actions/stale#1133 about it.

.github/workflows/stale.yml

@@ -4,6 +4,7 @@ on:
   schedule:
     - cron: '30 * * * *'
 permissions:
+  actions: write
   contents: write
   issues: write
   pull-requests: write