Update endpoints model

Author: aws-sdk-swift-automation

codegen/sdk-codegen/sdk-endpoints.json

@@ -5474,6 +5474,7 @@
           "ap-southeast-3" : { },
           "ap-southeast-4" : { },
           "ap-southeast-5" : { },
+          "ap-southeast-6" : { },
           "ap-southeast-7" : { },
           "ca-central-1" : { },
           "ca-west-1" : { },