Tweak dependabot schedule [ci skip]

Author: sue445

.github/dependabot.yml

@@ -43,7 +43,7 @@ updates:
   - package-ecosystem: bundler
     directory: /
     schedule:
-      interval: daily
+      interval: weekly
       time: "05:00"
       timezone: Asia/Tokyo
     open-pull-requests-limit: 99