Merge pull request #328 from maxmind/claude/dependabot-gitsubmodule

Enable Dependabot for git submodules (STF-1290)

Author: horgh

.github/dependabot.yml

@@ -17,3 +17,11 @@ updates:
       time: '14:00'
     cooldown:
       default-days: 7
+  - package-ecosystem: gitsubmodule
+    directory: /
+    schedule:
+      interval: weekly
+      day: monday
+      time: '14:00'
+    cooldown:
+      default-days: 7