add cooldown

Author: kevinjqliu

.github/dependabot.yml

@@ -26,7 +26,11 @@ updates:
     open-pull-requests-limit: 50
     ignore:
       - dependency-name: "datafusion"
+    cooldown:
+      default-days: 7
   - package-ecosystem: "github-actions"
     directory: "/"
     schedule:
       interval: "weekly"
+    cooldown:
+      default-days: 7