fix(approvals): correct DeadLetterConfig shape on state machine EventBridge rule

The PublicationApprovalRequestedEvent rule's DeadLetterConfig used {Type: SQS, Destination: ...} — a shape valid only for EventInvokeConfig.DestinationConfig.OnFailure, not for a rule DeadLetterConfig, which only accepts Arn/QueueLogicalId/Type. Fixed to {Arn: !GetAtt ApprovalsServiceDLQ.Arn}, matching the correct sibling rule's DLQ wiring on the same template. Same defect and fix as the .NET track.

Author: sliedig

unicorn_approvals/infrastructure/approvals-service/template.yaml

@@ -253,8 +253,7 @@ Resources:
               MaximumRetryAttempts: 5
               MaximumEventAgeInSeconds: 900
             DeadLetterConfig:
-              Type: SQS
-              Destination: !GetAtt ApprovalsServiceDLQ.Arn
+              Arn: !GetAtt ApprovalsServiceDLQ.Arn
       DefinitionSubstitutions:
         WaitForContractApprovalArn: !GetAtt WaitForContractApprovalFunction.Arn
         TableName: !Ref ContractStatusTable