Reduce AWS SDK Dependency Updating to monthly

This Renovate Bot configuration change will mean that PRs for `com.amazonaws:aws-java-sdk-s3` will be created only on the first day of each month. Existing (open) PRs will continue to get rebased (if conflicted) or updated (if a newer version gets released), but once the PR is merged or closed then another one won't be created again until the next month.

Discussion: https://github.com/apache/fineract/pull/1071#issuecomment-644957795

renovate.json

@@ -5,5 +5,10 @@
   "ignorePaths": [
     "docs/**"
   ],
-  "labels": ["renovate"]
+  "labels": ["renovate"],
+  "packageRules": [{
+    "description": "Limit the aws sdk to monthly updates because otherwise it PRs every day",
+    "packageNames": ["com.amazonaws:aws-java-sdk-s3"],
+    "schedule": ["monthly"]
+  }]
 }