SNS policy update

[mattp0]

Per @asjohnston-asf:

Aside, I'd consider limiting your policy to only allow the free SQS and Lambda subscriptions. That's the default setup for SNS topics for the AWS Open Data program, for example (cloudformation example). We don't have a use case outside of SQS at the moment.Aside, I'd consider limiting your policy to only allow the free SQS and Lambda subscriptions. That's the default setup for SNS topics for the AWS Open Data program, for example (cloudformation example). We don't have a use case outside of SQS at the moment.

Might be a good consideration to update the policy in: https://github.com/asfadmin/cumulus-task-granule-to-sns-notifier/blob/main/terraform/sns.tf