update github-actions dependabot configs

Author: kevinjqliu

.github/dependabot.yml

@@ -18,8 +18,11 @@
 
 version: 2
 updates:
+  # Maintain dependencies for GitHub Actions
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
-      interval: "daily"
-    open-pull-requests-limit: 10
+      interval: "weekly"
+      day: "sunday"
+    cooldown:
+      default-days: 7