chore: Set up Dependabot for 'gh-cache/delete'

Author: smockle

.github/dependabot.yml

@@ -23,6 +23,10 @@ updates:
     directory: "/.github/actions/gh-cache/cache"
     schedule:
       interval: "weekly"
+  - package-ecosystem: "github-actions"
+    directory: "/.github/actions/gh-cache/delete"
+    schedule:
+      interval: "weekly"
   - package-ecosystem: "github-actions"
     directory: "/.github/actions/gh-cache/restore"
     schedule: